利用虚函数实现多态性

#include<iostream>
#include<string>
using namespace std;
class Student
{
public:
	Student(int n,string nam,int s):num(n),name(nam),score(s) {}
	virtual void display()
	{
		cout<<"num: "<<num<<endl;
		cout<<"name: "<<name<<endl;
		cout<<"score: "<<score<<endl;
	}
protected:
	int num;
	string name;
	int score;
};
class Graduate:public Student
{
public:
	Graduate(int n,string nam,int s,int w):Student(n,nam,s),wage(w){}
	void display()
	{
		cout<<"num: "<<num<<endl;
		cout<<"name: "<<name<<endl;
		cout<<"score: "<<score<<endl;
		cout<<"wage: "<<wage<<endl;
	}
private:
	int wage;
};
int main()
{
	Student stu(10010,"wang",100);
	Graduate Grad(10020,"zhao",99,1000);
	Student *p=&stu;
	p->display();
	p=&Grad;
	p->display();
	return 0;
}