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Polymorphism 469

14

Listing 14.6 rewrites Listing 14.5 to take advantage of virtual derivation.

LISTING14.6 Illustration of the Use of Virtual Inheritance

0: // Listing 14.6

1: // Virtual inheritance

2: #include <iostream>

3: using namespace std;

4:

5: typedef int HANDS;

6: enum COLOR { Red, Green, Blue, Yellow, White, Black, Brown } ;

7:

8: class Animal // common base to both horse and bird

9: {

10: public:

11: Animal(int);

12: virtual ~Animal() { cout << “Animal destructor...\n”; }

13: virtual int GetAge() const { return itsAge; }

14: virtual void SetAge(int age) { itsAge = age; }

15: private:

16: int itsAge;

17: };

18:

19: Animal::Animal(int age):

20: itsAge(age)

21: {

22: cout << “Animal constructor...\n”;

23: }

24:

25: class Horse : virtual public Animal

FIGURE14.3
A diamond
inheritance. Animal

Horse Bird

Pegasus