用指向基类对象的指针输出数据

#include "stdafx.h"

#include<iostream>
#include<string>

using namespace std;

class student{
private:
 int num;
 int age;
 float score;
public:
 student(int ,int ,float);
 void display();
};

//定义构造函数
student::student(int n,int a,float sc):num(n),age(a),score(sc){}

void student::display(){//定义成员函数
 cout<<num<<endl;
 cout<<age<<endl;
 cout<<score<<endl;
}

class graduate:public student{
 private:
  float pay;
 public:
  graduate(int,int,float,float);
  void display();
};
 graduate::graduate(int n,int a,float sc,float p):student(n,a,sc),pay(p){}
 void graduate::display(){
  student::display();
  cout<<pay<<endl;
 }

 int main(){
  student st(12222,22,97.4);
  graduate gr(353543,26,88.2,8000);
  student *pt=&st;
  pt->display();
  pt=&gr;
  pt->display();
  return 0;
 }

 

输出结果:

12222
22
97.4

353543
26
88.2
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