STL !!!generic programming!!!
Anar Manafov ([email protected])
STL (Standard Template Library)or STL stands for Stepanov and Lee
The EvolutionSTL is not a new library as compared to other libraries. Originally, the development of the STL was started by Alexander Stepanov at HP in 1979. Later, he was joined by David Musser and Meng Lee. In 1994, STL was included into ANSI and ISO C++.
recommended link (Al Stevens Interviews Alex Stepanov, March 1995 issue of Dr. Dobb's Journal, ): http://www.sgi.com/tech/stl/drdobbs-interview.html
http://www.stepanovpapers.com/
STL Components
Here is a list of elements of the STL. The first three of them are fundamental items.
- Container (An object that holds other objects)- Algorithm (A function that acts on containers)- Iterator (A pointer-like object)
- Allocator (This item manages memory allocation in a container)- Adaptor (Transforms one object into another)- Predicate (A function that returns a boolean value, true or false.)- Function Object (A class that defines operator().)
Recommended link: http://www.sgi.com/tech/stl/ and http://www.sgi.com/tech/stl/stl_index.html
STL Components
containers, iterators, algorithms
vector <T>
list <T>
sort
find
containers, iterators, algorithms#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
int ia[10]={33,17,11,88,43,99,6,9,12,7};
int main(){
vector<int> x(ia,ia+10);
sort(x.begin(), x.end());
9 11 12 17 337 43 88 996
11 88 43 99 617 9 12 733
begin()end()
// grab value to search for
int s_value;
cin >> s_value;
// search for an element
vector<int>::iterator found;
found=find(x.begin(),x.end(),s_value);
if(found != x.end()) {
cout << "search value found!\n";
}
else {
cout << "search value not found!\n";
}
}
list instead of vector
#include <list>
#include <algorithm>
#include <iostream>
using namespace std;
int ia[10]={33,17,11,88,43,99,6,9,12,7};
int main(){
list<int> x(ia,ia+10);
sort(x.begin(), x.end());
// grab value to search for int s_value; cin >> s_value;
// search for an element list<int>::iterator found; found=find(x.begin(),x.end(),s_value); if(found != x.end()) { cout << "search value found!\n"; } else { cout << "search value not found!\n"; }}
Algorithms with built-in arrays
#include <algorithm>
#include <iostream>
using namespace std;
int ia[10]={33,17,11,88,43,99,6,9,12,7};
int main(){
int s_value;
cout << "enter search value: ";
cin >> s_value;
int *found;
found=find(&ia[0],&ia[10],s_value);
if(found != ia+10) ...
Containers
Sequence ContainersVector
List
Deque
Stack
Queue Adaptor
Priority_queue
Almost ContainersBuilt-in arrays, strings, valarrays, bitsets
Associative ContainersMap
Multimap
Set
Multiset
Containers
ContainerVector: Deque:
List:
Set/Multiset: Map/Multimap:
string Type#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
string s1("Hello");
string s2("World");
cout << s1 + " " + s2 + '\n';
string s3(s1 + " " + s2);
cout << '\"'<< s3 << "\" has " << s3.length()
<< " characters" << endl;
replace(s3.begin(), s3.end(), 'W', 'w');
cout << s3 << endl;
Constructors
container()
container(n) (not for ass. cont.)
container(n,x) (not for ass. cont.)
container(first,last)
container(c)
~container()
Stack, Queue, List Operations
push_back() pop_back()
push_front() pop_front()
insert(p,x)
insert(p,n,x)
insert(p,first,last)
erase(p)
erase(first,last)
clear()
Algorithms
• copy• sort• find• fill• partition• insert, delete• union, intersection• accumulate• ...
Iterators
• The glue that makes it possible to use generic algorithms and orthogonalize those algorithms from the data structures
• An iterator i is a generalized means of traversing a data structure:– for an array, an array index or a pointer
• Dereferencing an iterator, *i, is guaranteed to give the item, but an iterator does not obey all pointer operations
Iterators, Element Access
begin()
end()
rbegin()
rend()
front()
back()
[]
at()
Points to first element
Points to one-past-last element
Points to first element of reverse seq.
Points to one-past-last element of rev. seq.
First element
Last element
Subscripting, unchecked access
Subscripting, checked access
Iterator Operationsoutput input forward bidirectional random-access
Read =*p =*p =*p =*p
Access -> -> -> -> []
Write *p= *p= *p= *p=
Iteration ++ ++ ++ ++ -- ++ -- + -
Comparison == != == != == != == != < >
Iterators (continued)
container<T>::iterator first=c.begin();
container<T>::iterator last=c.end();
[first,last)
++i;
first == last;
i != last;
i + n; (long jump)
*i = x;
x = *i;
Nonmodifying Sequence Operations
for_each()
find()
find_if()
find_first_of()
adjacent_find()
count()
count_if()
mismatch()
equal()
search()
find_end()
search_n()
list<Person*> all;...for_each(all.begin(),all.end(),Print(cout));
Function objects
class bThan{
public:
bThan(int x): testVal(x) {}
const int testVal;
bool operator()(int val){return val>testVal;}
};
list<int>::iterator firstBig =
find_if(aList.begin(),aList.end(),bThan(12));
OO ?
• STL is not OO, is OOP dead?
• Not all problems are best solved in OOP fashion!
• Many problems are best solved in an OOP manner.
• Know as much as you can about as many styles of programming as you can, an use the style most appropriate to the problem.
#include <iostream>#include <map>#include <string>
using namespace std;
int main(){
map<string, long, less<string> > directory;
directory["Anar"] = 2128;directory["Victor"] = 1395;directory["Demo"] = 12344;
string name;while (cin >> name){
if ( directory.find(name) != directory.end() )cout << "The phone number for " << name << " is " << directory[name] << endl;
elsecout << "Sorry, no listing for " << name << endl;
}}
#include <iostream>#include <map>#include <string>
using namespace std;
typedef map<string, long, less<string> > Directory_t;typedef Directory_t::value_type Entry;
int main(){
Directory_t directory;// Will change the value of the key or insert if the key is exist alreadydirectory["Anar"] = 2128;// will insert or fail if the key is exist alreadydirectory.insert ( make_pair<string, long>("Victor", 1395) );directory.insert( Entry("Demo", 12344) );
string name;while (cin >> name){
Directory_t::iterator iter = directory.find(name);if ( iter != directory.end() )
cout << "The phone number for " << iter->first << " is " << (*iter).second << endl;else
cout << "Sorry, no listing for " << name << endl;}
}
/*! \fn void TrimRight(std::basic_string<_T> &_str, const std::basic_string<_T> &_Val)\brief Trims trailing characters from the string.\param _Val - [in] The target characters to be trimmed.
*/template<typename _T>void TrimRight(std::basic_string<_T> &_str, const std::basic_string<_T> &_Val){
_str.resize( _str.find_last_not_of( _Val ) + 1 );}
/*! \fn void TrimLeft(std::basic_string<_T> &_str, const std::basic_string<_T> &_Val)\brief Trims leading characters from the string.\param _Val - [in] The target characters to be trimmed.
*/template<typename _T>void TrimLeft(std::basic_string<_T> &_str, const std::basic_string<_T> &_Val){
_str.erase( 0, _str.find_first_not_of( _Val ) );}
Some real life examplessmall, but very handy!