sarojkumar21.panda

 Profile Answers by sarojkumar21.panda 

• Sep 1st, 2009

 

Which version of the function to be called is based upon the type of object pointed by the pointer.This determination of call is made at run time.As your question says the pointer is pointed to the derived object.So the call will be based upon the object pointed and in ur case it is the derived class function.

Execute the following programm and you will be clear.

#include<iostream>
#include<conio.h>

using namespace std;
class base
{
      public:
             virtual void display()
             {
                     cout<<"display function in base class"<<endl;
                    
                     }
};

class derived:public base
{
      public:
            
             void display()
             {
                  cout<<"dislay function in derived class"<<endl;
                  }
                  };
                 
                 
                 
                  int main()
                  {
                      base *bptr;
                      derived d1;
                      bptr=&d1;
                      bptr->display();
                      getch();
                      return 0;
                      }
                 


ans:;dislay function in derived class

newlife

 Profile Answers by newlife 

• Sep 17th, 2009

 

Whenever any class has virtual function then the binding is delayed till run time.

llifeinus

 Profile Answers by llifeinus 

• Sep 22nd, 2009

 

As explained, you have assigned the base class pointer to the derived class object, the derived class method will get called.

ajrobb

 Profile Answers by ajrobb 

• Sep 22nd, 2010

 

This is polymorphism, an object with at least one virtual method. When a polymorphic object is constructed, it includes a hidden vtable containing virtual function pointers and other polymorphic information. When a virtual method is invoked, it is called through the function pointer in the vtable.

When defining a polymorphic class, the first method I define would be a virtual destructor in the base class. Once a method is defined as virtual in a base class it will be virtual in a derived class. However, it is good manners to include the 'virtual' keyword in the derived class as it documents the intended polymorphism.

Vincent Monsen

 Profile Answers by Vincent Monsen 

• Jan 30th, 2011

 

The derived class method will be called because the method is declared virtual in the base class.  Dynamic binding enables this.