Description : swap() function is used to exchange the contents of two queues but the queues must be of same type, although sizes may differ.
Example:
// Take any two queues
std::queue<int> queue1, queue2;
// Fill queue1 with { 1, 2, 3, 4 }
for (int i=1; i<5; i++) {
queue1.push(i);
}
// Fill queue2 with { 10, 9, 8, 7, 6, 5 }
for (int i=10; i>4; i--) {
queue2.push(i);
}
// Swap elements of queues
queue1.swap(queue2);
// Print the first queue
std::cout << "queue1 = ";
while (!queue1.empty()) {
std::cout << queue1.front() << " ";
queue1.pop();
}
// Print the second queue
std::cout <<"\nqueue2 = ";
while (!queue2.empty()) {
std::cout << queue2.front() << " ";
queue2.pop();
}