040.cpp

// STL : Queues

#include <iostream>
#include <queue>

int main()
{
    // program to demonstrate queue of the standard template library of c++
    std::queue<char> q;

    // inserting elements into the queue
    for (int i = 0; i < 10; i++)
    {
        q.push('A' + i);
    }

    // printing the elements of the queue
    std::cout << "Queue : ";
    // using the empty function
    while (!q.empty())
    {
        std::cout << q.front() << " ";
        q.pop();
    }
    std::cout << std::endl;

    // size of the queue
    std::cout << "Size of the queue : " << q.size() << std::endl;

    // understanding the Swap func. of queue stl
    // first populating both queues
    for (int i = 0; i < 10; i++)
    {
        q.push('A' + i);
    }
    std::queue<char> q2;
    for (int i = 0; i < 10; i++)
    {
        q2.push('a' + i);
    }
    q.swap(q2);

    std::cout << "Queue 1 : ";
    while (!q.empty())
    {
        std::cout << q.front() << " ";
        q.pop();
    }
    std::cout << std::endl;

    std::cout << "Queue 2 : ";
    while (!q2.empty())
    {
        std::cout << q2.front() << " ";
        q2.pop();
    }
    std::cout << std::endl;
    return 0;
}