多态赋值

#include <iostream> 
using namespace std;
class Pet //基类
{ public:
   virtual void Speak() { cout<<"How does a pet speak ?"<<endl; } 
};
class Cat : public Pet //派生类
{public:
    void Speak() { cout<<"miao!miao!"<<endl; }
}; 
class Dog : public Pet //派生类
{public:
    void Speak() { cout<<"wang!wang!"<<endl; }
};
void test (Pet &testClass){
      testClass.Speak();
}

int main()
{
    Pet obj,*p1; //基类对象指针p1, 基类对象obj
    Dog dog1;
    Cat cat1; 
    obj = dog1; //用Dog类对象给Pet类对象赋值
    obj.Speak(); 
    p1 = &cat1; //用Cat类对象地址给基类指针赋值
    p1->Speak(); 
    p1 = &dog1; //用Dog类对象地址给基类指针赋值
    p1->Speak(); 
    Pet &p4 = cat1; //以Cat类对象初始化Pet类引用 
    p4 .Speak();
	test(dog1);
	system("pause");
    return 0;
}

  

输出是：How does a pet speak ?  miao!miao!   wang!wang!   miao!miao!  wang!wang!