用指向基类对象的指针输出数据

/*#include <iostream>
#include <string>
using namespace std;
class A
{
public:
A()
{
cout<<"基类的构造函数constructing A "<<endl;
}
~A()
{
cout<<"基类的析构函数destructing A "<<endl;
}
};
class B:public A
{
public:
B()
{
cout<<"派生类A的构造函数constructing A "<<endl;
}
~B()
{
cout<<"派生类A的析构函数destructing A "<<endl;
}
};
class C:public B
{
public:
C()
{
cout<<"派生类A的构造函数constructing C "<<endl;
}
~C()
{
cout<<"派生类A的析构函数destructing C "<<endl;
}
};
int main()
{
C c1;
return 0;
}*/
#include <iostream>
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()
{
Student stud1(1001,"Li",87.5);
Graduate grad1(2001,"Wang",98.5,563.5);
Student *pt=&stud1;
pt->display();
pt=&grad1;
pt->display();
return 0;
}