Path: utzoo!mnetor!uunet!mcvax!botter!ark!maart
From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.lang.c
Subject: Re: global data in C programming...
Message-ID: <1212@ark.cs.vu.nl>
Date: 17 Mar 88 23:40:28 GMT
References: <7506@ncoast.UUCP>
Reply-To: maart@cs.vu.nl (Maarten Litmaath)
Distribution: comp
Organization: VU Informatica, Amsterdam
Lines: 63
Keywords: global data, extern, C programming

In article <7506@ncoast.UUCP> btb@ncoast.UUCP (Brad Banko) writes:
\...

\x.h:
\	int i,j;
\
\x.c:
\#include "x.h"
\
\xyz() {
\	i = ...
\}
\
\y.c:
\#include "x.h"
\
\zzt() {
\	i = j ...
\}

\...

You have to reserve space for the variables only in one file, in the
other files you must declare the variables "extern", so the following
is a beautiful solution (thanks to Paul Polderman [polder@cs.vu.nl]):
--------------------------------------------------------------------
global.h:

#ifndef	GLOBAL
#define	GLOBAL	extern
#endif	GLOBAL

GLOBAL	int	i, j;
--------------------------------------------------------------------
global.c:

#define	GLOBAL
#include	"global.h"
--------------------------------------------------------------------
x.c:

#include	"global.h"

xyz()
{
	i = ...
}
--------------------------------------------------------------------
y.c:

#include	"global.h"

zzt()
{
	i = j ...
}
--------------------------------------------------------------------
cc x.c y.c global.c
--------------------------------------------------------------------
Regards.
-- 
South-Africa:                         |Maarten Litmaath @ Free U Amsterdam:
           revival of the Third Reich |maart@cs.vu.nl, mcvax!botter!ark!maart