c12-2-2.cpp

这我们老师对是面向对象程序设计（清华大学出版社）一书制作的PPT

#include <iostream>
#include <string>
using namespace std;
class Student
 {public:
   Student(int,string,float);
   virtual void display();
  protected:
   int num;
   string name;
   float score;
 };

Student::Student(int n,string nam,float s)
 {num=n;name=nam;score=s;}

void Student::display()
 {cout<<"num:"<<num<<"\nname:"<<name<<"\nscore:"<<score<<"\n\n";}
 
class Graduate:public Student
 {public:
   Graduate(int,string,float,float);
   void display();
 private:
  float pay;
};

void Graduate::display()
 {cout<<"num:"<<num<<"\nname:"<<name<<"\nscore:"<<score<<"\npay="<<pay<<endl;}

Graduate::Graduate(int n,string nam,float s,float p):Student(n,nam,s),pay(p){}

int main()
 {Student stud1(1001,"Li",87.5);
  Graduate grad1(2001,"Wang",98.5,1200);
  Student *pt=&stud1;
  pt->display();
  pt=&grad1;
  pt->display();
  return 0;
 }