#include <iostream.h>


class parent
{
public:

   int i1;

   virtual void f1()
   {
      i1 = i1 + 100;
      cout << "**** parent method increases i1" << endl;
   }
};

class child : public parent
{
public:

   virtual void f1()
   {
      i1 = i1 - 100;
      cout << "child method DEcreases i1" << endl;
   }
};

int main(int argc, char **argv)
{
   parent *p;
   child  *q;

   child  y;


   y.i1 = 400;

   // ------------------------------------------------------------
   y.f1();				// invoke f1() in child
   cout << "y.i1 = " << y.i1 << endl;

   // ------------------------------------------------------------
   q = &y;
   q->f1();				// invoke f1() in child
   cout << "y.i1 = " << y.i1 << endl;

   // ------------------------------------------------------------
   p = &y;
   p->f1();				// invoke f1() in parent !!!
   cout << "y.i1 = " << y.i1 << endl;
}