//Listing 12.11 Virtual copy constructor
#include <iostream>
using namespace std;class Mammal
{public:Mammal():itsAge(1) { cout << "Mammal constructor...\n"; }virtual ~Mammal() { cout << "Mammal destructor...\n"; }Mammal (const Mammal & rhs);virtual void Speak() const { 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())
{cout << "Mammal Copy Constructor...\n";
}class Dog : public Mammal
{public:Dog() { cout << "Dog constructor...\n"; }virtual ~Dog() { cout << "Dog destructor...\n"; }Dog (const Dog & rhs);void Speak()const { cout << "Woof!\n"; }virtual Mammal* Clone() { return new Dog(*this); } // 这里！
};Dog::Dog(const Dog & rhs):
Mammal(rhs)
{cout << "Dog copy constructor...\n";
}class Cat : public Mammal
{public:Cat() { cout << "Cat constructor...\n"; }~Cat() { cout << "Cat destructor...\n"; }Cat (const Cat &);void Speak()const { cout << "Meow!\n"; }virtual Mammal* Clone() { return new Cat(*this); }
};Cat::Cat(const Cat & rhs):
Mammal(rhs)
{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++){cout << "(1)dog (2)cat (3)Mammal: ";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;
}