Program:use of virtual function

include<iostream.h>
class Base
{ 
public: 
void display() 
{   
cout<<"\n Display Base"; 
}
virtual void show() 
{   
cout<<"\n Show Base:"; 
}
};
class Derived : public Base
{ 
public: 
void display() 
{   
cout<<"\n Display Derived"; 
}
void show() 
{   
cout<<"\n Show Derived"; 
}
};
int main()
{ 
Base B; 
Derived D; 
Base *bptr;
cout<<"\n bptr points to Base\n"; 
bptr = &B; 
bptr ->display (); 
bptr ->show ();
cout<<"\n\n bptr points to derived\n"; 
bptr = &D; 
bptr ->display (); 
bptr ->show ();
return 0;
}