Point/Circle Hierarchy using protected data

Figure 4.15: Point2 class represents an xy-coordinate pair as protected data.

Figure 4.16: Circle3 class header file.

Figure 4.17: Circle3 class that inherits from class Point2.

Figure 4.18: Protected base-class data can be accessed from derived class. (part 1 of 2)

Figure 4.19: Protected base-class data can be accessed from derived class. (part 2 of 2)

Using protected data members

• Advantages
  • Derived classes can modify values directly
  • Slight increase in performance; avoid set/get function call overhead
• Disadvantages
  • No validity checking; derived class can assign illegal value
  • Implementation dependent
    • Derived class member functions more likely dependent on base class implementation
    • Base class implementation changes may result in derived class modifications; fragile (brittle) software