C++ program to use Abstract Class

#include <iostream>
using namespace std;
class GrandFather //Abstract Class
{
    char name1[20];
    public:
        virtual void read()=0;
        virtual void show()=0;
};
class Father:public GrandFather
{
    char name2[20];
    public:
        void read()
        {
            cout<<"Enter father name: ";
            cin>>name2;
        }
        void show()
        {
            cout<<endl<<"Father name: "<<name2<<endl;
        }
};
class Son:public Father
{
    char name3[20];
    public:
        void read()
        {
            cout<<"Enter son name: ";
            cin>>name3;
        }
        void show()
        {
            cout<<endl<<"Son name: "<<name3<<endl;
        }
};
int main()
{
    GrandFather *gf;
    Father f;
    Son s;
    gf=&f;
    gf->read();
    gf->show();
    gf=&s;
    gf->read();
    gf->show();
    return 0;
}