学步园

#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;
}

这个程序非常体现多态性,运行时才决定调用哪一个函数,Mammal* ptr;指针在运行时才决定调用哪一个派生类的函数

 

作者: 林羽飞扬
出处：http://www.cnblogs.com/zhengyuhong/
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