基类与派生类的转换

#include <iostream>
#include <string.h>
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;

class Student
{
    public:
        Student(int,string,float);
        void display();
    private:
        int num;
        string name;
        float score;
};

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

void Student::display()
{
    cout<<endl<<"num:"<<num<<endl;
    cout<<"name:"<<name<<endl;
    cout<<"score:"<<score<<endl;
}

class Graduate:public Student
{
    public:
        Graduate(int,string,float,float);
        void display();
    private:
        float pay;
};
Graduate::Graduate(int n,string nam,float s,float p):Student(n,nam,s),pay(p){
    
}
void Graduate::display()
{
    Student::display();
    cout<<"pay="<<pay<<endl;
}
int main(int argc, char** argv) {
    Student stud1(1001,"li",99);
    Graduate grad1(2001,"wang",99,443);
    Student *pt=&stud1;
    pt->display();
    pt=&grad1;
    pt->display();
    return 0;
}