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From: James Dennett <jdennett@acm.org>
Newsgroups: comp.std.c++,comp.lang.c++
Subject: Re: Inheritance Problems
Date: Thu, 10 May 2001 23:41:35 GMT
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"O.Petzold" wrote:
> 
> Hello,
> 
> the follwoing code isn't working (with the gcc-2.95.2).
> If I see the inharritance it should !
> 
> class A {
> public:
>   void ModifyAnother(A* a2) {
>     b = 1;              // is working
>     a2->b = 1;          // woking as well
>   }
> protected:
>   int b;
> };
> 
> 
> class B : public A {
> public:
>   void ModifyAnother(A* a2)  {
>     b = 1;              // is working
>     a2->b = 1;          // not working
>   }
> };
> 
> int main() {
>     B b;
> }
> 
> `int A::b' is protected
> 
> Well but, B is derived from A !!
> What says the standard about ?

That objects of class B have access to protected parts
of objects that are themselves of class B, not to any
other objects which are A's (or instances of subclasses
of A which aren't subclasses of B).

-- James Dennett

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