Invoking Base-Class Functions from Derived-Class Objects

Aim pointers (base, derived) at objects (base, derived)

• Base pointer aimed at base object
• Derived pointer aimed at derived object; both straightforward
• Base pointer aimed at derived object
  • "is a" relationship; Circle "is a" Point
  • Will invoke base class functions
• Function call depends on the class of the pointer/handle
  • Does not depend on object to which it points
  • With virtual functions, this can be changed (more later)

Figure 5.1: Point class header file.

Figure 5.2: Point class represents an xy-coordinate pair.

Figure 4.7: Circle class header file.

Figure 5.4: Circle class that inherits from class Point.

Figure 5.5: Assigning addresses of base-class and derived-class objects to base-class and derived-class pointers. (part 1 of 2)

Figure 5.6: Assigning addresses of base-class and derived-class objects to base-class and derived-class pointers. (part 2 of 2)