#include <iostream>class Person{public:	virtual void say(){		std::cout<<"person"<<std::endl;	}};class Student:public Person{public:	void say(){		std::cout<<"student"<<std::endl;	}};int main(){	Person per;	Student stud;	per.say();	stud.say();	//传递对象	per = stud;	per.say();	//指针	Person *pPtr = &stud;	pPtr->say();	//引用	Person &pRef = stud;	pRef.say();}