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;}