//Listing 17.4 Virtual copy constructor

 #include <iostream>

 

 class Mammal

 {

 public:

     Mammal():itsAge(1) { std::cout << "Mammal constructor...\n"; }

     virtual ~Mammal() { std::cout << "Mammal destructor...\n"; }

     Mammal (const Mammal & rhs);

     virtual void Speak() const { std::cout << "Mammal speak!\n"; }

     virtual Mammal* Clone() { return new Mammal(*this); } 

     int GetAge()const { return itsAge; }

 

 protected:

     int itsAge;

 };

 

 Mammal::Mammal (const Mammal & rhs):itsAge(rhs.GetAge())

 {

     std::cout << "Mammal Copy Constructor...\n";

 }

 

 class Dog : public Mammal

 {

 public:

     Dog() { std::cout << "Dog constructor...\n"; }

     virtual ~Dog() { std::cout << "Dog destructor...\n"; }

     Dog (const Dog & rhs);

     void Speak()const { std::cout << "Woof!\n"; }

     virtual Mammal* Clone() { return new Dog(*this); }

 };

 

 Dog::Dog(const Dog & rhs):

 Mammal(rhs)

 {

     std::cout << "Dog copy constructor...\n";

 }

 

 class Cat : public Mammal

 {

 public:

     Cat() { std::cout << "Cat constructor...\n"; }

     virtual ~Cat() { std::cout << "Cat destructor...\n"; }

     Cat (const Cat &);

     void Speak()const { std::cout << "Meow!\n"; }

     virtual Mammal* Clone() { return new Cat(*this); }

 };

 

 Cat::Cat(const Cat & rhs):

 Mammal(rhs)

 {

     std::cout << "Cat copy constructor...\n";

 }

 

 enum ANIMALS { MAMMAL, DOG, CAT};

 const int NumAnimalTypes = 3;

 int main()

 {

     Mammal *theArray[NumAnimalTypes];

     Mammal* ptr;

     int choice,i;

     for (i = 0; i<NumAnimalTypes; i++)

     {

         std::cout << "(1)dog (2)cat (3)Mammal: ";

         std::cin >> choice;

         switch (choice)

         {

         case DOG: 

             ptr = new Dog;

             break;

         case CAT: 

             ptr = new Cat;

             break;

         default: 

             ptr = new Mammal;

             break;

         }

         theArray[i] = ptr;

     }

     Mammal *OtherArray[NumAnimalTypes];

     for (i=0;i<NumAnimalTypes;i++)

     {

         theArray[i]->Speak();

         OtherArray[i] = theArray[i]->Clone();

     }

     for (i=0;i<NumAnimalTypes;i++)

         OtherArray[i]->Speak();

     return 0;

 }