all queue functions

// Queue is a container adapter that gives
// the programmer a FIFO (first-in, first-out)
// data structure. 
// push, pop, size, front, back, empty
#include <iostream>
#include <queue>
#include <string>
using namespace std;

int main ()
{
    string s1("C++");
    string s2("is");
    string s3("powerfull");
    string s4("language");

    queue que;
    que.push(s1);
    que.push(s2);
    que.push(s3);
    que.push(s4);

    cout << "size of queue 'que' = "
         << que.size() << endl;

    string temp = que.back();
    cout << temp << endl;

    while ( !que.empty() )
    {
        temp = que.front();
        cout << temp << " ";
        que.pop();
    }
    cout << endl;
    return 0;
}
OUTPUT:
// size of queue 'que' = 4
// language
// C++ is powerfull language