#include <queue>
  bool empty() const;

The empty() function returns true if the queue has no elements, false otherwise.

For example, the following code uses empty() as the stopping condition on a while loop to clear a queue while displaying its contents:

 queue<int> q;
 for( int i = 0; i < 5; i++ ) {
   q.push(i);
 }
 while( !q.empty() ) {
   cout << q.front() << endl;
   q.pop();
 }