4elist1209.cpp

《21天学通C＋＋》附盘的原代码。书上的每个例子在这里都有相应的C语言程序。

//Listing 12.9 Multiple virtual functions called in turn

#include <iostream>
using namespace std;

class Mammal
{
public:
	Mammal():itsAge(1) {  }
	virtual ~Mammal() { }
	virtual void Speak() const { cout << "Mammal speak!\n"; }
protected:
	int itsAge;
};

class Dog : public Mammal
{
public:
	void Speak()const { cout << "Woof!\n"; }
};


class Cat : public Mammal
{
public:
	void Speak()const { cout << "Meow!\n"; }
};


class Horse : public Mammal
{
public:
	void Speak()const { cout << "Winnie!\n"; }
};

class Pig : public Mammal
{
public:
	void Speak()const { cout << "Oink!\n"; }
};

int main()
{
	Mammal* theArray[5];
	Mammal* ptr;
	int choice, i;
	for ( i = 0; i<5; i++)
	{
		cout << "(1)dog (2)cat (3)horse (4)pig: ";
		cin >> choice;
		switch (choice)
		{
		case 1: ptr = new Dog;
				break;
		case 2: ptr = new Cat;
				break;
		case 3: ptr = new Horse;
				break;
		case 4: ptr = new Pig;
				break;
		default: ptr = new Mammal;
				break;
		}
		theArray[i] = ptr;
	}
	for (i=0;i<5;i++)
		theArray[i]->Speak();
	return 0;
}