#include <vector>
  bool empty() const;

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

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

  vector<int> v;
  for( int i = 0; i < 5; i++ ) {
    v.push_back(i);
  }
  while( !v.empty() ) {
    cout << v.back() << endl;
    v.pop_back();
  }