Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!adm!PEPRBV%CFAAMP.BITNET@husc6.harvard.EDU
From: PEPRBV%CFAAMP.BITNET@husc6.harvard.EDU (Bob Babcock)
Newsgroups: comp.lang.c
Subject: Re: global data in C programming...
Message-ID: <12471@brl-adm.ARPA>
Date: 17 Mar 88 18:48:43 GMT
Sender: news@brl-adm.ARPA
Lines: 14

>>how does one use global data in C programming?

Basically, the global variables should be declared with the extern
keyword in every source file but one.  (Note that this is really
a linker requirement; I'm not sure whether all environments require
this.)  The way I do this is in the include file, I put
   EXTERN int x,y;
in main (before the file is included) I put
   #define EXTERN
and in all other routines I put
   #define EXTERN extern
If the global variable is explicitly initialized, you need to put in
#ifdef's of some sort so that the initialization is only done where the
extern keyword is absent.