Description : back() function is used to reference the last element (i.e the newest element) of the queue. This function can be used to fetch the last element of a queue.
Example:
// Empty queue
std::queue<int> myqueue;
// Add elements to queue using push()
myqueue.push(2);
myqueue.push(5);
myqueue.push(4);
myqueue.push(1);
// Queue becomes 2, 5, 4, 1
// Print the last/newest element in the queue
std::cout << myqueue.back();