RE: [Dev-C++] Virtual functions?

[Somanathan K. <som...@wi...>]

I hope you are familiar with pointers. Its needs a good understanding of
pointers. See the below example,

Class base=20
{
	public:
		virtual void f1(){=20
               ...body ...
            }
};

class derived1 : public base
{
	public:
		virtual void f1(){ // virtual or not doesn't matter here
			...body...
            }
}

class derived2 : public base
{
	public:
		virtual void f1(){
		   ... body...
            }
}

int main()
{
  base* b;
  derived1* d1 =3D new derived1;
  derived2* d2 =3D new derived2;=20
  b =3D d1;
  b->f1(); //this calls the derived1 f1
  b=3Dd2;
  b->f1(); //this call the derived2 f1
 // u should delete the objects....
} =20

this is a simple example, but in actual usage, it will be bit different
(Objects may be pooled in a list/array etc.).  =20


-----Original Message-----
From: pr...@le... [mailto:pr...@le...]=20
Sent: Monday, July 21, 2003 3:34 PM
To: dev...@li...
Subject: [Dev-C++] Virtual functions?

Hi List,

I've been through numerous books & websites on this topic, but I _still_
can't quite understand what is the purpose of a virtual function.

From what I understand, a virtual function is defined in a base class,
but
isn't implemented there. The implementation goes in the derived class.
Now
if this is true, then why should I need to define a function in my base
class at all? Since I'm eventually going to implement it elsewhere, I
might
as well define it there too.

Am I even on the right track here? Can someone take me back to base
again?

Thanks.

Regards,
Pranav Negandhi




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