// In this example, the pointer is of type base but it points to the derived class object.
// The method display() is virtual in nature. Hence in order to resolve the virtual method
// call, the context of the pointer is considered, i.e., the display method of the derived
// class is called and not that of the base. If the method was non virtual in nature, the
// display() method of the base class would have been called. 

#include <iostream>

using namespace std;

class base
{
public:

virtual void display()
{
  cout<<"\nBase";
}

};

class derived : public base
{
  public:

  void display()
  {
     cout<<"\nDerived";
  }

};

int main()
{
  base *ptr = new derived();
  ptr->display();
  getchar();
  return 0;
}