C++ LANGUAGE STANDARD TEMPLATE LIBRARY

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C++ LANGUAGE STANDARD TEMPLATE LIBRARY

STANDARD TEMPLATE LIBRARY 


Hope you have already understood the concept of C++ Template 
which we have discussed earlier. The C++ STL 
(Standard Template Library) is a powerful set of 
C++ template classes to provide general-purpose 
classes and functions with templates that implement 
many popular and commonly used algorithms and data 
structures like vectors, lists, queues, and stacks. 

At the core of the C++ Standard Template Library are 
following three well-structured components: 




Component  Description 
Containers  Containers are used to manage collections 
                of objects of a certain kind. There are several 
                different types of containers like deque, 
                list, vector, map etc. 

Algorithms  Algorithms act on containers. They provide 
               the means by which you will perform initialization, 
               sorting, searching, and transforming of the contents of containers.
 
Iterators  Iterators are used to step through the 
                elements of collections of objects. These collections 
                may be containers or subsets of containers. 

We will discuss about all the three C++ STL components in 
next chapter while discussing C++ Standard Library. 
For now, keep in mind that all the three components 
have a rich set of pre-defined functions which help 
us in doing complicated tasks in very easy fashion. 

Let us take the following program that demonstrates 
the vector container (a C++ Standard Template) which 
is similar to an array with an exception that it 
automatically handles its own storage requirements 
in case it grows: 

#include <iostream> 
#include <vector> 
using namespace std; 
  
int main() 
{ 
39. STL TUTORIAL 
   // create a vector to store int 
   vector<int> vec;  
   int i; 
 
   // display the original size of vec 
   cout << "vector size = " << vec.size() << endl; 
 
   // push 5 values into the vector 
   for(i = 0; i < 5; i++){ 
      vec.push_back(i); 
   } 
 
   // display extended size of vec 
   cout << "extended vector size = " << vec.size() << endl; 
 
   // access 5 values from the vector 
   for(i = 0; i < 5; i++){ 
      cout << "value of vec [" << i << "] = " << vec[i] << endl; 
   } 
 
   // use iterator to access the values 
   vector<int>::iterator v = vec.begin(); 
   while( v != vec.end()) { 
      cout << "value of v = " << *v << endl; 
      v++; 
   } 
 
   return 0; 
} 
When the above code is compiled and executed, it produces the following result: 
vector size = 0 
extended vector size = 5 
value of vec [0] = 0 
value of vec [1] = 1 
value of vec [2] = 2 
value of vec [3] = 3 
value of vec [4] = 4 
value of v = 0 
value of v = 1 
value of v = 2 
value of v = 3 
value of v = 4