hour18_1.cpp

《24学时精通c++》的随书源码的下半部分。欢迎下载学习。

 // Listing 18.7
 // Deriving ADTs from other ADTs
 #include <iostream>
 
 enum COLOR { Red, Green, Blue, Yellow, White, Black, Brown } ;
 
 class Animal        // common base to both horse and bird
 {
 public:
     Animal(int);
     virtual ~Animal() { std::cout << "Animal destructor...\n"; }
     virtual int GetAge() const { return itsAge; }
     virtual void SetAge(int age) { itsAge = age; }
     virtual void Sleep() const = 0;
     virtual void Eat() const = 0;
     virtual void Reproduce() const = 0;
     virtual void Move() const = 0;
     virtual void Speak() const = 0;
 private:
     int itsAge;
 };
 
 Animal::Animal(int age):
 itsAge(age)
 {
     std::cout << "Animal constructor...\n";
 }
 
 class Mammal : public Animal
 {
 public:
     Mammal(int age):Animal(age)
         { std::cout << "Mammal constructor...\n";}
     virtual ~Mammal() { std::cout << "Mammal destructor...\n";}
     virtual void Reproduce() const 
         { std::cout << "Mammal reproduction depicted...\n"; }
 };
 
 class Fish : public Animal
 {
 public:
     Fish(int age):Animal(age)
         { std::cout << "Fish constructor...\n";}
     virtual ~Fish() 
         { std::cout << "Fish destructor...\n";  }
     virtual void Sleep() const 
         { std::cout << "fish snoring...\n"; }
     virtual void Eat() const 
         { std::cout << "fish feeding...\n"; }
     virtual void Reproduce() const 
         { std::cout << "fish laying eggs...\n"; }
     virtual void Move() const 
         { std::cout << "fish swimming...\n";   }
     virtual void Speak() const { }
 };
 
 class Horse : public Mammal
 {
 public:
     Horse(int age, COLOR color ):
         Mammal(age), itsColor(color) 
         { std::cout << "Horse constructor...\n"; }
     virtual ~Horse() 
         { std::cout << "Horse destructor...\n"; }
     virtual void Speak()const 
         { std::cout << "Whinny!... \n"; }
     virtual COLOR GetItsColor() const 
         { return itsColor; }
     virtual void Sleep() const 
         { std::cout << "Horse snoring...\n"; }
     virtual void Eat() const 
         { std::cout << "Horse feeding...\n"; }
     virtual void Move() const 
         { std::cout << "Horse running...\n";}
 
 protected:
     COLOR itsColor;
 };
 
 class Dog : public Mammal
 {
 public:
     Dog(int age, COLOR color ):
         Mammal(age), itsColor(color) 
         { std::cout << "Dog constructor...\n"; }
     virtual ~Dog() 
         { std::cout << "Dog destructor...\n"; }
     virtual void Speak()const 
         { std::cout << "Whoof!... \n"; }
     virtual void Sleep() const 
         { std::cout << "Dog snoring...\n"; }
     virtual void Eat() const 
         { std::cout << "Dog eating...\n"; }
     virtual void Move() const  
         { std::cout << "Dog running...\n"; }
     virtual void Reproduce() const 
         { std::cout << "Dogs reproducing...\n"; }
 
 protected:
     COLOR itsColor;
 };
 
 int main()
 {
     Animal *pAnimal=0;
     int choice;
     bool fQuit = false;
 
     while (1)
     {
         std::cout << "(1)Dog (2)Horse (3)Fish (0)Quit: ";
         std::cin >> choice;
 
         switch (choice)
         {
         case 1: 
             pAnimal = new Dog(5,Brown);
             break;
         case 2: 
             pAnimal = new Horse(4,Black);
             break;
         case 3: 
             pAnimal = new Fish (5);
             break;
         default: 
             fQuit = true;
             break;
         }
         if (fQuit)
             break;
 
         pAnimal->Speak();
         pAnimal->Eat();
         pAnimal->Reproduce();
         pAnimal->Move();
         pAnimal->Sleep();
         delete pAnimal;
         std::cout << "\n";
     }

     pAnimal = new Animal (5);   // new animal
                                 // The line above will produce a compiler error 
                                 // because Animal is an abstract class and cannot
                                 // be directly instantiated! The compiler knows it
                                 // is abstract because a method contains "const = 0"
                                 // (Animal::Sleep for instance).
     std::cout << "new animal: \n";
     pAnimal->Speak();
     pAnimal->Eat();
     pAnimal->Reproduce();
     pAnimal->Move();
     pAnimal->Sleep();

     delete pAnimal;
     std::cout << "\n";
     

     return 0;
 }