Sams Teach Yourself C++ in 21 Days

Polymorphism 485

14

101: switch (choice)

102: {

103: case 1: pAnimal = new Dog(5,Brown);

104: break;

105: case 2: pAnimal = new Horse(4,Black);

106: break;

107: case 3: pAnimal = new Fish (5);

108: break;

109: default: fQuit = true;

110: break;

111: }

112: if (fQuit == false)

113: {

114: pAnimal->Speak();

115: pAnimal->Eat();

116: pAnimal->Reproduce();

117: pAnimal->Move();

118: pAnimal->Sleep();

119: delete pAnimal;

120: cout << endl;

121: }

122: }

123: return 0;

124: }

(1)Dog (2)Horse (3)Bird (0)Quit: 1

Animal constructor...

Mammal constructor...

Dog constructor...

Whoof!...

Dog eating...

Dog reproducing....

Dog running...

Dog snoring...

Dog destructor...

Mammal destructor...

Animal destructor...

(1)Dog (2)Horse (3)Bird (0)Quit: 0

On lines 7–21, the abstract class Animalis declared. Animalhas nonpure virtual

accessors for itsAge, which are shared by all Animalobjects. It has five pure vir-

tual functions,Sleep(),Eat(),Reproduce(),Move(), and Speak().

Mammalis derived from Animalon lines 29–37, and adds no data. It overrides

Reproduce(), however, providing a common form of reproduction for all mammals. Fish

must override Reproduce()because Fishderives directly from Animaland cannot take

OUTPUT

LISTING14.10 continued

ANALYSIS