//Example 9.1:派生類對(duì)象替換基類對(duì)象
#include <iostream.h> 
class Pet 						//基類
{
public:
	void Speak()
	{ cout<<"How does a pet speak ?"<<endl; } 
};
class Cat : public Pet 			//派生類
{
public:
	void Speak()
	{ cout<<"miao!miao!"<<endl; }
}; 
class Dog : public Pet			//派生類
{
public:
	void Speak()
	{ cout<<"wang!wang!"<<endl; }
};
void main()
{
	Pet	*p1, *p2, *p3,obj;		//基類對(duì)象指針p1, 基類對(duì)象obj
	Dog dog1;
	Cat cat1; 
	obj = dog1;				//用Dog類對(duì)象給Pet類對(duì)象賦值
	obj.Speak();	
	p1 = &cat1; 				//用Cat類對(duì)象地址給基類指針賦值
	p1->Speak(); 
	p1 = &dog1; 				//用Dog類對(duì)象地址給基類指針賦值
	p1->Speak(); 
	p2=new Cat;				//動(dòng)態(tài)生成Cat類對(duì)象
	p2->Speak();
	p3=new Dog;				//動(dòng)態(tài)生成Dog類對(duì)象
	p3->Speak();
	Pet	&p4 = cat1;			//以Cat類對(duì)象初始化Pet類引用 
	p4 .Speak();
}