Path: chuka.playstation.co.uk!news
From: Philip Gooch <philg@nospam.easynet.co.uk>
Newsgroups: scee.yaroze.beginners
Subject: Re: Object files and linking
Date: Sun, 19 Jul 1998 02:13:21 +0100
Organization: philg@nospam.easynet.co.uk
Lines: 46
Message-ID: <35B1482F.94AB6660@nospam.easynet.co.uk>
References: <35AE6952.2D94C5E9@scee.sony.co.uk> <35AF91D1.CCE4F782@compuserve.com> <35AFB921.F692044A@scee.sony.co.uk>
Reply-To: philg@nospam.easynet.co.uk
NNTP-Posting-Host: philg.easynet.co.uk
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii; x-mac-type="54455854"; x-mac-creator="4D4F5353"
Content-Transfer-Encoding: 7bit
X-Mailer: Mozilla 4.04 (Macintosh; I; PPC)



James Russell wrote:

> Nick Slaven wrote:
> >
> > It might be worth mentioning pre processor directives (I think thats the name).
>
> I use them in a similar way:
>
> If I've got Graphics.c which has globals that must be accessed by other modules, I do this:
>
> Graphics.c:
> #define _GRAPHICS_C
> #include "graphics.h"
> ...
> yadda yadda yadda
> ...
>
> Graphics.h
> #ifndef _GRAPHICS_C
> #define GRAPHICS_EXTERN extern
> #else
> #define GRAPHICS_EXTERN
> #endif
>
> GRAPHICS_EXTERN int banana;
> GRAPHICS_EXTERN int wibble;
>
> Thus, in Graphics.C, wibble and banana are defined without the 'extern' keyword, but if I include
> graphics.h in any other file, they are defined 'extern'. banana and wibble are not defined in
> Graphics.c, but graphics.h. I'm sure there must be a better way of doing this though.
>
> Cheers,
>
> James
> .

  All this stuff is very useful. Thanks guys.

Basically the way I see it, you add the #ifndef stuff in your header file to prevent the same things
being defined twice (which can happen if you #include the same header files in multiple source
files)

Phil