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8/6/2019 Different Data Types in C
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Submitted by :Manish Mann
ECE/09/128
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` Data Type: set of values together with a set of
operations is called a data type
` Data types are used to store various types of data
that is processed by program.
` Data type attaches with variable to determine the
number of bytes to be allocate to variable and
valid operations which can be performed on thatvariable.
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` C data can be classified into four categories:
Fundamental data types
Data type modifiers
Derived data types
UserDefined data types
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` Fundamental data types are those that are notcomposed of any other data types.
Five types of fundamental data types are:-
1. int data type (for integers):
Examples: 0
-6728
91
No commas are used within an integer.Size: 2 bytes
Range: -32768 to 32767
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2. char data type (forcharacters):
The smallest integral data type.
Used for characters: letters, digits, and special symbols.
Each character is enclosed in single quotes.
Examples: 'A,'a', '0', '*', '+', '$', '&.A blank space is a character and is written ' ', with a space.
Size : 1 byte
Range : -128 to 127
3. float data type (for floating point numbers):It represents any real number.Size : 4 bytesRange: 3.4 * 10-38 to 3.4 * 1038 -1
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4. double data type (for double precision floatingpoint
numbers):
it is used to define BIG floating point numbers.
It reserves twice the storage for the number.
Size : 8 bytesRange : 3.4 * 10-4932 to 3.4 * 104932 -1
5. void data type :
It specifies the empty set of values.
It is used for the functions that doesn't return value.
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` The data types explained above have the followingmodifiers.
1. short
2. long
3. signed
4. unsigned
` The modifiers define the amount of storage allocated tothe variable. The amount of storage allocated is not cast instone. ANSI has the following rules:
o short int
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Types Size (in bytes) Range
short int 2 -32,768 -> +32,767
unsigned sh
ort int 2 0 -> +65,535unsigned int 4 0 -> +4,294,967,295
long int 4 -2,147,483,648 -> +2,147,483,647
signed int 2 same as int
signedchar 1 -128 -> +127
unsignedchar 1 0 -> +255float 4
double 8
long double 12
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` The Data types that are derived from the
fundamental data types.
` The types of derived data types are:
1. Arrays
2. Functions
3. Pointers
4. References
5. Constants
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` Arrays are used in C to represent structures of
consecutive elements of the same type. The definition
of a (fixed-size) array has the following syntax:
int array[100];
which defines an array named array to hold 100
values of theprimitive type int.
` If declared within a function, the array dimension may
also be a non-constant expression, in which case
memory for the specified number of elements will be
allocated.
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` A function is a named part of a program that can be invoked fromother parts of the programs as often needed.
` Syntax of function:
type fuction-name(parameter list)
{.
body of function
}
` A function must have a return statement.
` A function can be invoked by two manners:
1.Call by value: It copies the values of actual parameters and
creates its own copy of arguments and uses them.2.Call by reference : It doesnt create a copy and directly refers
to the original parameters only different name i.e references.
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` In declarations , the asterisk modifier (*) specifies apointer type.
` For example, where the specifier int would refer to theinteger type, the specifier int * refers to the type
"pointer to integer".` The following line of code declares a pointer-to-integer
variable called ptr:
int *ptr;
` Pointer values associate two pieces of information:1. Memory address
2. Data type
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` A reference is an alternative name for a object.
` A reference variable provides an alias for a previously
defined variable.
` Its declaration consist of a
base type, an
&
(ampersand) and a reference variable name.
` In the following example, ptr is set so that it points to
the data associated with the variable a:
int *ptr;
int a;
ptr = &a;
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` The keyword const can be added to the
declaration of an object to make that object a
constant rather than a variable.
` The value of the named constant cannot bealtered during program run.
` Syntax:
const type name = value;
` So it must be initialized at the time of declaration.
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` The UserDefined data types are that derived data
types which are defined by the user
` The types of user defined derived data types are :
1. structure
2. union
3. enumeration
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` A structure is a variables referenced under one name,providing a convinient means of keeping related informantiontogether.
` The variables that make up structure are called structureelements.
` Keyword struct is used to construct a structure.
` Syntax :
struct name{
structure elements;
};` A structure is diff. from an array as, array is the collection of
similar data types where as structure is collection of diff. datatypes.
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` Unions in C are related to structures and are defined
as objects that may hold (at different times) objects of
different types and sizes.
` They are analogous to variant records in other.
` Unlike structures, the components of a union all refer
to the same location in memory programming
languages.
` The size of a union is equal to the size of its largest
component type.
` Keyword union is used to declare and create a union.
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` Used to create a group of values which are named constants in C,
C++, C#, Java, etc.
` Examples in C/C++/C#:
enum days {Mon, Tue, Wed, Thu, Fri, Sat, Sun}; //Mon = 0, Tues = 1, .
. ., etc.
days today, yesterday = Wed;
today = yesterday + 1;
` The first constant in an enumeration is assigned the value zero, and
each subsequent value is incremented by one over the previous
constant.
` Specific values may also be assigned to constants in the
declaration, and any subsequent constants without specific values
will be given incremented values from that point onward.
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` The reason for providing so many data types is to
allow programmer to take advantage of hardware
characteristics.
` Helps in avoiding wastage in memory.
` Helps in avoiding wastege of time.
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