源程序：

#include <iostream>
using namespace std;class Person
{
public:
  virtual void disp()
  {
    cout<<"Person  ";
  }
};
class Address:public Person  //程序填空
{
public:
  void disp()
  {
    cout<<"Address"<<endl;
  }
};class PhoneNumber:public Person
{
public:
  void disp()
  {
    cout<<"PhoneNumber"<<endl;
  }
};
void main()
{
  Person *p;
  Address a;
  PhoneNumber pn;
  p=&a;
  p->Person::disp();  //显示Person
  p->disp();   //显示Address
  p=&pn;
  p->Person::disp();  //程序填空 显示Person
  p->disp();   //显示PhoneNumber
}

 结果：