Relationships Among Objects in an Inheritance Hierarchy

• Previously (Section 9.4),
  • Circle inherited from Point
  • Manipulated Point and Circle objects using member functions
• Now
  • Invoke functions using base-class/derived-class pointers
  • Introduce virtual functions
• Key concept
  • Derived-class object can be treated as base-class object
    • "is-a" relationship
    • Base class is not a derived class object