C++ STL Tutorial
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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 −
| Sr.No | Component & Description |
|---|---|
| 1 |
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. |
| 2 |
Algorithms Algorithms act on containers. They provide the means by which you will perform initialization, sorting, searching, and transforming of the contents of containers. |
| 3 |
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() {
// 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
Here are following points to be noted related to various functions we used in the above example −
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The push_back( ) member function inserts value at the end of the vector, expanding its size as needed.
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The size( ) function displays the size of the vector.
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The function begin( ) returns an iterator to the start of the vector.
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The function end( ) returns an iterator to the end of the vector.
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