#include <stack>
  bool empty() const;

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

For example, the following code uses empty() as the stopping condition on a while loop to clear a stack and display its contents in reverse order:

 stack<int> s;
 for( int i = 0; i < 5; i++ ) {
   s.push(i);
 }
 while( !s.empty() ) {
   cout << s.top() << endl;
   s.pop();
 }