Consider a container class (chptr. 16), and programmers P1 and P2:

• P1 develops a stack that P2 will use
• P2 is ignorant of the implementation details, needs only the interface:

  Stack s;
  s.push(3.14);
  s.push(1.41);
  s.push(2.76);
  while (s.size() > 0)
  {
     cout << s.top() << "\n";
     s.pop();
  }