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Streams and IOStreams and IO
Streams are pipe like constructors used for Streams are pipe like constructors used for providing IOproviding IO
When a programmer needs to handle input When a programmer needs to handle input from or output to external entitiesthen from or output to external entitiesthen streams are used by c++streams are used by c++
The stream is the central concept of the The stream is the central concept of the iostream classesiostream classes
Output streamsOutput streams
An output stream object is a destination for bytes An output stream object is a destination for bytes The three most important output stream classare The three most important output stream classare
ostreamostream ofstreamofstream and ostrstream and ostrstreamThe The ostreamostream class through the derived class class through the derived class
basic_ostreambasic_ostream supports the predefined stream supports the predefined stream objectsobjectscoutcout standard output standard output
cerrcerr standard error with limited buffering standard error with limited buffering clogclog similar to similar to cerrcerr but with full buffering but with full buffering
Input streamsInput streams
An input stream object is a source of bytes The three An input stream object is a source of bytes The three most important input stream classes are most important input stream classes are istreamistream ifstreamifstream
and and istrstreamistrstreamThe istream class is best used for sequential text-mode The istream class is best used for sequential text-mode
input You can configure objects of class istream for input You can configure objects of class istream for buffered or unbuffered operation All functionality of the buffered or unbuffered operation All functionality of the
base classios is included in istream You will base classios is included in istream You will rarelconstruct objects from class istream Instead you will rarelconstruct objects from class istream Instead you will generally use the predefined generally use the predefined cincin object which is actually object which is actually
an object of class an object of class ostreamostream In some cases you can In some cases you can assign assign cincin to other stream objects after program startup to other stream objects after program startup
Formatting IOFormatting IO Formatting using Ios functionsFormatting using Ios functions
Width()-It specifies the width for displaythe output will take up the Width()-It specifies the width for displaythe output will take up the width specifiedused in alignng vertical column of numeric itemswidth specifiedused in alignng vertical column of numeric items
Precision()-It specifies the precision of the floating point Precision()-It specifies the precision of the floating point numberDefault precision is six digits after decimal pointnumberDefault precision is six digits after decimal point
Fill()-it specifies the character for filling up the unused prion of the Fill()-it specifies the character for filling up the unused prion of the fieldIt is usually usd with the width member functionfieldIt is usually usd with the width member function
Setf()-The function specifies the format flags that controls output Setf()-The function specifies the format flags that controls output display like left or right justificationpadding after sign display like left or right justificationpadding after sign symbolscientific notation displaydisplaying abse of the numbersymbolscientific notation displaydisplaying abse of the number
Unsetf()-This function provides undo operation for above mentioned Unsetf()-This function provides undo operation for above mentioned operations with setfoperations with setf
The prototype of the function isThe prototype of the function is
ltltold value of streamgtfunction old value of streamgtfunction nameltspecified new valuenameltspecified new valuegtgt
The functions set new value to the stream and The functions set new value to the stream and retutn valueThe width function sets new width to retutn valueThe width function sets new width to
the argument specified and returns old widthThe the argument specified and returns old widthThe precision function sets new precision and returns precision function sets new precision and returns
old precisionold precision
Member functions of Ios
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Output streamsOutput streams
An output stream object is a destination for bytes An output stream object is a destination for bytes The three most important output stream classare The three most important output stream classare
ostreamostream ofstreamofstream and ostrstream and ostrstreamThe The ostreamostream class through the derived class class through the derived class
basic_ostreambasic_ostream supports the predefined stream supports the predefined stream objectsobjectscoutcout standard output standard output
cerrcerr standard error with limited buffering standard error with limited buffering clogclog similar to similar to cerrcerr but with full buffering but with full buffering
Input streamsInput streams
An input stream object is a source of bytes The three An input stream object is a source of bytes The three most important input stream classes are most important input stream classes are istreamistream ifstreamifstream
and and istrstreamistrstreamThe istream class is best used for sequential text-mode The istream class is best used for sequential text-mode
input You can configure objects of class istream for input You can configure objects of class istream for buffered or unbuffered operation All functionality of the buffered or unbuffered operation All functionality of the
base classios is included in istream You will base classios is included in istream You will rarelconstruct objects from class istream Instead you will rarelconstruct objects from class istream Instead you will generally use the predefined generally use the predefined cincin object which is actually object which is actually
an object of class an object of class ostreamostream In some cases you can In some cases you can assign assign cincin to other stream objects after program startup to other stream objects after program startup
Formatting IOFormatting IO Formatting using Ios functionsFormatting using Ios functions
Width()-It specifies the width for displaythe output will take up the Width()-It specifies the width for displaythe output will take up the width specifiedused in alignng vertical column of numeric itemswidth specifiedused in alignng vertical column of numeric items
Precision()-It specifies the precision of the floating point Precision()-It specifies the precision of the floating point numberDefault precision is six digits after decimal pointnumberDefault precision is six digits after decimal point
Fill()-it specifies the character for filling up the unused prion of the Fill()-it specifies the character for filling up the unused prion of the fieldIt is usually usd with the width member functionfieldIt is usually usd with the width member function
Setf()-The function specifies the format flags that controls output Setf()-The function specifies the format flags that controls output display like left or right justificationpadding after sign display like left or right justificationpadding after sign symbolscientific notation displaydisplaying abse of the numbersymbolscientific notation displaydisplaying abse of the number
Unsetf()-This function provides undo operation for above mentioned Unsetf()-This function provides undo operation for above mentioned operations with setfoperations with setf
The prototype of the function isThe prototype of the function is
ltltold value of streamgtfunction old value of streamgtfunction nameltspecified new valuenameltspecified new valuegtgt
The functions set new value to the stream and The functions set new value to the stream and retutn valueThe width function sets new width to retutn valueThe width function sets new width to
the argument specified and returns old widthThe the argument specified and returns old widthThe precision function sets new precision and returns precision function sets new precision and returns
old precisionold precision
Member functions of Ios
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Input streamsInput streams
An input stream object is a source of bytes The three An input stream object is a source of bytes The three most important input stream classes are most important input stream classes are istreamistream ifstreamifstream
and and istrstreamistrstreamThe istream class is best used for sequential text-mode The istream class is best used for sequential text-mode
input You can configure objects of class istream for input You can configure objects of class istream for buffered or unbuffered operation All functionality of the buffered or unbuffered operation All functionality of the
base classios is included in istream You will base classios is included in istream You will rarelconstruct objects from class istream Instead you will rarelconstruct objects from class istream Instead you will generally use the predefined generally use the predefined cincin object which is actually object which is actually
an object of class an object of class ostreamostream In some cases you can In some cases you can assign assign cincin to other stream objects after program startup to other stream objects after program startup
Formatting IOFormatting IO Formatting using Ios functionsFormatting using Ios functions
Width()-It specifies the width for displaythe output will take up the Width()-It specifies the width for displaythe output will take up the width specifiedused in alignng vertical column of numeric itemswidth specifiedused in alignng vertical column of numeric items
Precision()-It specifies the precision of the floating point Precision()-It specifies the precision of the floating point numberDefault precision is six digits after decimal pointnumberDefault precision is six digits after decimal point
Fill()-it specifies the character for filling up the unused prion of the Fill()-it specifies the character for filling up the unused prion of the fieldIt is usually usd with the width member functionfieldIt is usually usd with the width member function
Setf()-The function specifies the format flags that controls output Setf()-The function specifies the format flags that controls output display like left or right justificationpadding after sign display like left or right justificationpadding after sign symbolscientific notation displaydisplaying abse of the numbersymbolscientific notation displaydisplaying abse of the number
Unsetf()-This function provides undo operation for above mentioned Unsetf()-This function provides undo operation for above mentioned operations with setfoperations with setf
The prototype of the function isThe prototype of the function is
ltltold value of streamgtfunction old value of streamgtfunction nameltspecified new valuenameltspecified new valuegtgt
The functions set new value to the stream and The functions set new value to the stream and retutn valueThe width function sets new width to retutn valueThe width function sets new width to
the argument specified and returns old widthThe the argument specified and returns old widthThe precision function sets new precision and returns precision function sets new precision and returns
old precisionold precision
Member functions of Ios
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Formatting IOFormatting IO Formatting using Ios functionsFormatting using Ios functions
Width()-It specifies the width for displaythe output will take up the Width()-It specifies the width for displaythe output will take up the width specifiedused in alignng vertical column of numeric itemswidth specifiedused in alignng vertical column of numeric items
Precision()-It specifies the precision of the floating point Precision()-It specifies the precision of the floating point numberDefault precision is six digits after decimal pointnumberDefault precision is six digits after decimal point
Fill()-it specifies the character for filling up the unused prion of the Fill()-it specifies the character for filling up the unused prion of the fieldIt is usually usd with the width member functionfieldIt is usually usd with the width member function
Setf()-The function specifies the format flags that controls output Setf()-The function specifies the format flags that controls output display like left or right justificationpadding after sign display like left or right justificationpadding after sign symbolscientific notation displaydisplaying abse of the numbersymbolscientific notation displaydisplaying abse of the number
Unsetf()-This function provides undo operation for above mentioned Unsetf()-This function provides undo operation for above mentioned operations with setfoperations with setf
The prototype of the function isThe prototype of the function is
ltltold value of streamgtfunction old value of streamgtfunction nameltspecified new valuenameltspecified new valuegtgt
The functions set new value to the stream and The functions set new value to the stream and retutn valueThe width function sets new width to retutn valueThe width function sets new width to
the argument specified and returns old widthThe the argument specified and returns old widthThe precision function sets new precision and returns precision function sets new precision and returns
old precisionold precision
Member functions of Ios
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
The prototype of the function isThe prototype of the function is
ltltold value of streamgtfunction old value of streamgtfunction nameltspecified new valuenameltspecified new valuegtgt
The functions set new value to the stream and The functions set new value to the stream and retutn valueThe width function sets new width to retutn valueThe width function sets new width to
the argument specified and returns old widthThe the argument specified and returns old widthThe precision function sets new precision and returns precision function sets new precision and returns
old precisionold precision
Member functions of Ios
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
IO manipulatorsIO manipulators
Manipulators are special functions for Manipulators are special functions for formattingformatting
The choice between manipulators and ios The choice between manipulators and ios functions to solve formatting problems functions to solve formatting problems
sometimes depends upon the usersometimes depends upon the userEquivalent manipulators for some of the io Equivalent manipulators for some of the io
functions arefunctions areSetw()setprecision()setfill()setiosflags()reseSetw()setprecision()setfill()setiosflags()rese
tiosflagstiosflags()()
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Unlike Iosmanipulators do not return the Unlike Iosmanipulators do not return the previous statusprevious status
Manipulators can write our own manipulator Manipulators can write our own manipulator and use it in the programmarksheet printing and use it in the programmarksheet printing
program can use it for printingprogram can use it for printingIos functions are singleThey cannot be Ios functions are singleThey cannot be
combined to have multiple effects combined to have multiple effects togetherWhen a large set of formatting togetherWhen a large set of formatting
options are usedmanipulators are used to options are usedmanipulators are used to write and produce more readable codewrite and produce more readable code
Ios functions need ltiotsreamgtwhereas Ios functions need ltiotsreamgtwhereas manipulators need ltiomanipmanipulators need ltiomanipltlt
Difference between ios and manipulators
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
include ltiostreamhgtinclude ltiostreamhgtinclude ltfstreamhgtinclude ltfstreamhgt
Input using cin Input using cin
int main () int main () char myline[256] char myline[256]
int lc = 0 int lc = 0
ofstream outfile(demotxtiosapp) ofstream outfile(demotxtiosapp)
ifstream infile(stdcodesxyz) ifstream infile(stdcodesxyz) if ( infile) if ( infile)
cerr ltlt Failed to open input filen cerr ltlt Failed to open input filen exit(1) exit(1)
while (1) while (1) infilegetline(myline256) infilegetline(myline256)
if (infileeof()) break if (infileeof()) break lc++ lc++
outfile ltlt lc ltlt ltlt myline ltlt n outfile ltlt lc ltlt ltlt myline ltlt n
infileclose() infileclose() outfileclose() outfileclose()
cout ltlt Output ltlt lc ltlt records ltlt endl cout ltlt Output ltlt lc ltlt records ltlt endl
Example program
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Object SerializationObject Serialization
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Object SerializationObject Serialization
Simple persistence method which provides a Simple persistence method which provides a program the ability to read or write a whole object program the ability to read or write a whole object
to and from a stream of bytesto and from a stream of bytesAllows Java objects to be encoded into a byte Allows Java objects to be encoded into a byte
stream suitable for streaming to a file on disk or stream suitable for streaming to a file on disk or over a networkover a network
The class must implement the The class must implement the SerializableSerializable interface (interface (javaioSerializablejavaioSerializable) which does not ) which does not
declare any methods and have accessors and declare any methods and have accessors and mutators for its attributesmutators for its attributes
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Object Serialization example pgmObject Serialization example pgm
create output streamcreate output stream
File file = new File file = new File(teams_serializeser)File(teams_serializeser)
String fullPath = filegetAbsolutePathString fullPath = filegetAbsolutePath()()
fos = new FileOutputStream(fullPath)fos = new FileOutputStream(fullPath)
open output stream and store team t1open output stream and store team t1
out = new ObjectOutputStream(fos)out = new ObjectOutputStream(fos)
outwriteObject(t1)outwriteObject(t1)
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Object persistenceObject persistence
One of the most critical tasks that applications One of the most critical tasks that applications have to perform is to save and restore datahave to perform is to save and restore data
PersistencePersistence is the storage of data from working is the storage of data from working memory so that it can be restored when the memory so that it can be restored when the
application is run againapplication is run againIn object-oriented systems there are several In object-oriented systems there are several
ways in which objects can be made persistentways in which objects can be made persistentThe choice of persistence method is an The choice of persistence method is an
important part of the design of an applicationimportant part of the design of an application
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
C++ NamespacesC++ Namespaces
A mechanism for logically grouping A mechanism for logically grouping declarations and definitions into a common declarations and definitions into a common
declarative regiondeclarative region
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
C++ NamespacesC++ Namespaces
The contents of the namespace can be The contents of the namespace can be accessed by code inside or outside the accessed by code inside or outside the
namespacenamespacendashUse the scope resolution operator to access Use the scope resolution operator to access
elements from outside the namespaceelements from outside the namespacendashAlternatively the Alternatively the usingusing declaration allows the declaration allows the
names of the elements to be used directlynames of the elements to be used directly
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
C++ NamespacesC++ Namespaces
Creating a namespaceCreating a namespacenamespace smallNamespacenamespace smallNamespace
intint count = 0 count = 0 voidvoid abc abc()()
end smallNamespaceend smallNamespace
Using a namespaceUsing a namespaceusingusing namespacenamespace smallNamespace smallNamespace
count +=1count +=1abcabc () ()
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
STD NamespacesSTD Namespaces
Items declared in the C++ Standard Library Items declared in the C++ Standard Library are declared in the are declared in the std std namespacenamespace
C++ C++ includeinclude files for several functions are in files for several functions are in the the std std namespacenamespace
ndashTo include input and output functions from the To include input and output functions from the C++ library writeC++ library write include ltiostreaminclude ltiostreamltlt
usingusing namespacenamespace std std
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Ansi string objectsAnsi string objects
The ANSI string class implements a first-class character string data type that avoids
many problemsassociated with simple character arrays
(C-style strings) You can define a string object very
simply as shown in the following example
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Ansi string class syntax pgmAnsi string class syntax pgm
include ltstringltusing namespace stdstring first_name = Bjarnestring last_namelast_name = Stroustrupstring names = first_name + + last_namecout ltlt names ltlt endlnames = last_name + + first + first_namecout ltlt names ltlt endl
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Ansi string class member functionsAnsi string class member functions
Member functionsThe string class defines many member functions A few of the basic
ones are described belowA string object may defined without an initializing value in which case
its initialvalue is an empty string (zero length no characters)string str1A string object may also be initialized with1048698 a string expressionstring str2 = str1string str3 = str1 + str2string str4 (str2) Alternate form1048698 a character string literalstring str4 = Hello there
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Standard Template LibraryStandard Template LibraryThe standard template library (STL) containsThe standard template library (STL) contains
ndashContainersContainersndashAlgorithmsAlgorithmsndashIteratorsIterators
A A containercontainer is a way that stored data is organized in is a way that stored data is organized in memory for example an array of elementsmemory for example an array of elements
AlgorithmsAlgorithms in the STL are procedures that are applied to in the STL are procedures that are applied to containers to process their data for example search for containers to process their data for example search for
an element in an array or sort an arrayan element in an array or sort an arrayIteratorsIterators are a generalization of the concept of pointers are a generalization of the concept of pointers
they point to elements in a container for example you they point to elements in a container for example you can increment an iterator to point to the next element in can increment an iterator to point to the next element in
an arrayan array
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Containers Iterators AlgorithmsContainers Iterators Algorithms
Container
AlgorithmIterator
Container
Iterator
Algorithm
Objects
Iterator
Iterator
Algorithm
Algorithms use iterators to interact with objectsstored in containers
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
ContainersContainers
A container is a way to store data either built-in dataA container is a way to store data either built-in data types like int and float or class objectstypes like int and float or class objectsThe STL provides several basic kinds of containersThe STL provides several basic kinds of containers
ndashgtgtvectorgt one-dimensional arrayvectorgt one-dimensional arrayndashgtgtlistgt double linked listlistgt double linked listndashgtgtdequegt double-ended queuedequegt double-ended queuendashgtgtqueuegt queuequeuegt queuendashgtgtstackgt stackstackgt stackndashgtgtsetgt setsetgt setndashgtgtmapgt associative arraymapgt associative array
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Sequence ContainersSequence ContainersA sequence container stores a set of elements inA sequence container stores a set of elements in
sequence in other words each element (exceptsequence in other words each element (except for the first and last one) is preceded by onefor the first and last one) is preceded by one specific element and followed by another ltvectorspecific element and followed by another ltvectorltlt
gt gt listgt and ltdequegt are sequential containerslistgt and ltdequegt are sequential containersIn an ordinary C++ array the size is fixed and canIn an ordinary C++ array the size is fixed and can
not change during run-time it is also tedious tonot change during run-time it is also tedious to insert or delete elements Advantage quick insert or delete elements Advantage quick
randomrandom accessaccess gtgtvectorgt is an expandable array that can shrink orvectorgt is an expandable array that can shrink or
grow in size but still has the disadvantage ofgrow in size but still has the disadvantage of inserting or deleting elements in the middleinserting or deleting elements in the middle
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Sequence ContainersSequence Containers
gtgtlistgt is a double linked list (each element haslistgt is a double linked list (each element has points to its successor and predecessor) it ispoints to its successor and predecessor) it is quick to insert or delete elements but has slowquick to insert or delete elements but has slow random accessrandom accessgtgtdequegt is a double-ended queue that means onedequegt is a double-ended queue that means one
can insert and delete elements from both ends itcan insert and delete elements from both ends it is a kind of combination between a stack (last inis a kind of combination between a stack (last in first out) and a queue (first in first out) and constitutes first out) and a queue (first in first out) and constitutes
a compromise between a ltvectorgt anda compromise between a ltvectorgt and a ltlista ltlistltlt
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Associative ContainersAssociative Containers
An associative container is non-sequential but An associative container is non-sequential but usesuses
a a keykey to access elements The keys typically to access elements The keys typically a number or a string are used by the a number or a string are used by the
container to arrange the stored elements in a container to arrange the stored elements in a specific orderspecific order
for example in a dictionary the entries are for example in a dictionary the entries are orderedordered
alphabeticallyalphabetically
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Associative ContainersAssociative ContainersA ltsetgt stores a number of items which contain keysA ltsetgt stores a number of items which contain keys
The keys are the attributes used to order the itemsThe keys are the attributes used to order the items
for example a set might store objects of the classfor example a set might store objects of the class
Person which are ordered alphabetically using their namePerson which are ordered alphabetically using their nameA ltmapgt stores pairs of objects a key object andA ltmapgt stores pairs of objects a key object and
an associated value object A ltmapgt is somehowan associated value object A ltmapgt is somehow
similar to an array except instead of accessing itssimilar to an array except instead of accessing its
elements with index numbers you access them withelements with index numbers you access them with
indices of an arbitrary typeindices of an arbitrary typegtgtsetgt and ltmapgt only allow one key of each valuesetgt and ltmapgt only allow one key of each value
whereas ltmultisetgt and ltmultimapgt allow multiplewhereas ltmultisetgt and ltmultimapgt allow multiple
identical key valuesidentical key values
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
vectorltintgt
array_
IteratorsIteratorsIterators are pointer-like entities that are Iterators are pointer-like entities that are
used toused to
access individual elements in a containeraccess individual elements in a containerOften they are used to move sequentially Often they are used to move sequentially
from element to element a process called from element to element a process called iteratingiterating through a container through a container
17
4
23
12
size_ 4
vectorltintgtiterator
The iterator corresponding tothe class vectorltintgt is ofthe type vectorltintgtiterator
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
IteratorsIteratorsOne can have multiple iterators pointing to One can have multiple iterators pointing to
different or identical elements in the different or identical elements in the containercontainervectorltintgt v
array_ 17
4
23
12
size_ 4i3
i1
i2
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
IteratorsIteratorsinclude ltvectoinclude ltvectorrltlt
include ltiostreaminclude ltiostreamltlt
int arr[] = 12 3 17 8 standard C arrayint arr[] = 12 3 17 8 standard C array
vectorltintgt v(arr arr+4) initialize vector with C arrayvectorltintgt v(arr arr+4) initialize vector with C array
for (vectorltintgtiterator i=vbegin() i=vend() i++)for (vectorltintgtiterator i=vbegin() i=vend() i++)
initialize i with pointer to first element of vinitialize i with pointer to first element of v
i++ increment iterator move iterator to next elementi++ increment iterator move iterator to next element
cout ltlt i ltlt rdquo rdquo de-referencing iterator returns thecout ltlt i ltlt rdquo rdquo de-referencing iterator returns the
value of the element the iterator points atvalue of the element the iterator points at
cout ltlt endlcout ltlt endl
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
File handling in CFile handling in C++++
Introduction to File HandlingIntroduction to File HandlingndashData entered once required later againData entered once required later againndashSame Data to be used by othersSame Data to be used by othersndashData required again by the same programData required again by the same program
Files and StreamsFiles and Streams
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
IO StreamsIO Streams
StreamDescription
cinStandard input stream
coutStandard output stream
cerrStandard error stream
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
ofstreamofstream
Output file stream ClassOutput file stream Classopen() is a member function of the class ofstreamopen() is a member function of the class ofstreamInherited functions of ofstream class from the class Inherited functions of ofstream class from the class
ostream areostream arendashputput()()ndashwritewrite()()ndashseekpseekp()()ndashtellptellp()()
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
fstreamfstream
It supports files for simultaneous input and outputIt supports files for simultaneous input and outputfstream is derived fromfstream is derived from
ndashifstreamifstreamndashofstreamofstreamndashiostreamiostream
They are parent classes and fstream is the child classThey are parent classes and fstream is the child classMember functions of the class fstreamMember functions of the class fstream
ndashopenopenndashcloseclosendashclose allclose allndashseekgseekgndashseekpseekpndashtellgtellgndashtellptellp
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
This program creates a file called ldquomessagedatThis program creates a file called ldquomessagedatrdquordquoinclude ltfstreamhgt include ltfstreamhgt Required for file IORequired for file IO
int mainint main()()
ofstream myfile (ldquomessagedatrdquo)ofstream myfile (ldquomessagedatrdquo)If (myfile)If (myfile)
check if the file is opened or notcheck if the file is opened or not
coutltltn Cannot open this filecoutltltn Cannot open this filereturn 1return 1
myfile ltltldquoWhen an apple fell Newton was disturbed nmyfile ltltldquoWhen an apple fell Newton was disturbed nrdquordquo
myfile ltltldquobut when he found that all apples fell nmyfile ltltldquobut when he found that all apples fell nrdquordquomyfile ltltldquomyfile ltltldquoit was gravitation that attracts them downit was gravitation that attracts them downnnrdquordquo
myfile ltltldquomyfile ltltldquohe was satisfied he was satisfied nnrdquordquomyfileclose()myfileclose()close the fileclose the file
return 1return 1
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
Function in CFunction in C++++
Function PrototypeFunction PrototypeFunction CallFunction CallFunction DefinitionFunction Definition
