gives the programmer the functionality of a queue (FIFO) - Dieptranivsr/DroneIVSR GitHub Wiki

Queues are a type of container adaptors which operate in a first in first out (FIFO) type of arrangement

The functions supported by queue are:

1. empty() – Returns whether the queue is empty.
2. size() – Returns the size of the queue.
3. queue::swap() in C++ STL: Exchange the contents of two queues but the queues must be of same type, although sizes may differ.
4. queue::emplace() in C++ STL: Insert a new element into the queue container, the new element is added to the end of the queue.
5. queue::front() and queue::back() in C++ STL– front() function returns a reference to the first element of the queue. back() function returns a reference to the last element of the queue.
6. push(g) and pop() – push() function adds the element 'g' at the end of the queue. pop() function deletes the first element of the queue.

// CPP code to illustrate
// Queue in Standard Template Library (STL)
#include <iostream>
#include <queue>

using namespace std;

// Print the queue
void showq(queue<int> gq)
{
	queue<int> g = gq;
	while (!g.empty()) {
		cout << '\t' << g.front();
		g.pop();
	}
	cout << '\n';
}

// Driver Code
int main()
{
	queue<int> gquiz;
	gquiz.push(10);
	gquiz.push(20);
	gquiz.push(30);

	cout << "The queue gquiz is : ";
	showq(gquiz);

	cout << "\ngquiz.size() : " << gquiz.size();
	cout << "\ngquiz.front() : " << gquiz.front();
	cout << "\ngquiz.back() : " << gquiz.back();

	cout << "\ngquiz.pop() : ";
	gquiz.pop();
	showq(gquiz);

	return 0;
}

Output

  The queue gquiz is :     10    20    30

  gquiz.size() : 3
  gquiz.front() : 10
  gquiz.back() : 30
  gquiz.pop() :     20    30