Program:

    #include <iostream.h>
    #include<conio.h>

    class bclass
    {
    public:
    virtual void message1(void)
    {
    cout<<"\nYou are Using message1() in bclass\n";
    }
    virtual void message2(void)
    {
    cout<<"\nYou are Using message2() in bclass\n";
    }
    };
    class dclass:public bclass
    {
    public:
    void message1(void)
    {
    cout<<"\nYou are Using message1() in dclass\n";
    }
    void message2(void)
    {
    cout<<"\nYou are Using message2() in dclass\n";
    }
    };
    void main()
    {
    clrscr(0;
    bclass *ptr;
    coit<<"ptr is a pointer to bclass\n\n";
    bclass obj1;
    dclass obj2;
    ptr=&obj1;
    ptr->message1();
    ptr->message2();
    ptr=&obj2;
    cout<<"\nptr is now pointing to dclass\n\n";
    ptr->message1();
    ptr->message2();
    getch();
    }