virt.cpp

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// virt.cpp
// virtual functions accessed from pointer
#include <iostream>
using namespace std;
////////////////////////////////////////////////////////////////
class Base                        //base class
   {
   public:
      virtual void show()         //virtual function
         { cout << "Base\n"; }
   };
////////////////////////////////////////////////////////////////
class Derv1 : public Base         //derived class 1
   {
   public:
      void show()
         { cout << "Derv1\n"; }
   };
////////////////////////////////////////////////////////////////
class Derv2 : public Base         //derived class 2
   {
   public:
      void show()
         { cout << "Derv2\n"; }
   };
////////////////////////////////////////////////////////////////
int main()
   {
   Derv1 dv1;           //object of derived class 1
   Derv2 dv2;           //object of derived class 2
   Base* ptr;           //pointer to base class

   ptr = &dv1;          //put address of dv1 in pointer
   ptr->show();         //execute show()

   ptr = &dv2;          //put address of dv2 in pointer
   ptr->show();         //execute show()
   return 0;
   }