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From: grimlok@hubcap.clemson.edu (Mike Percy)
Newsgroups: comp.lang.c
Subject: Re: Correct or Not or Old-fashioned or Bug
Message-ID: <1991May21.170939.6702@hubcap.clemson.edu>
Date: 21 May 91 17:09:39 GMT
References: <ZHOUMI.91May20182038@marlboro.nff.ncl.omron.co.jp> <1991May21.150735.12200@convex.com>
Distribution: comp.lang.c
Organization: Clemson University
Lines: 58

grogers@convex.com (Geoffrey Rogers) writes:

>In article <ZHOUMI.91May20182038@marlboro.nff.ncl.omron.co.jp> zhoumi@nff.ncl.omron.co.jp (Zhou Mi) writes:
>>
>One of the ways that I got around this problem of only having one file
>with all of my externals is to do the following:

>-------------- file 1 (pro_all.h) ----------------------
>#ifndef EXTERN
>#define EXTERN	extern
>#endif

>EXTERN int i;

>------------- file 2 (pro_main.c) ----------------------
>#define EXTERN

>#include "pro_all.h"

>void main()
>{
>	sub1();
>	sub2();
>	sub3();
>}

>--------- file 3 (pro_sub1.c) --------
>#include "pro_all.h"
>void sub1()
>{
>	i = 1;
>}

I've seen people do this kind of thing a lot, but I've never liked
having to remeber to put #define EXTERN or some such in my code.  I've
found it easiest to confine my global data to two files:
globals.h
  extern int foo;
  extern double bar;  
  /* and so on, declaring all global variables */
 
and
globals.c
  int foo;
  double bar;
  /* rest of the definitions */

Since I've started doing this, I've not had any problems related to
global data.  One problem is on certain segmented machines, in certain
compilers memory models, I take a hit because of the segment
placement.

Comments?

"I don't know about your brain, but mine is really...bossy."
Mike Percy                    grimlok@hubcap.clemson.edu
ISD, Clemson University       mspercy@clemson.BITNET
(803)656-3780                 mspercy@clemson.clemson.edu