Path: utzoo!attcan!uunet!husc6!bloom-beacon!mit-eddie!ll-xn!ames!oliveb!pyramid!markhall
From: markhall@pyramid.pyramid.com (Mark Hall)
Newsgroups: comp.lang.c
Subject: Re: Help needed with #include problems
Message-ID: <24341@pyramid.pyramid.com>
Date: 23 May 88 18:26:21 GMT
References: <28400001@ntvax> <6104@sigi.Colorado.EDU> <2955@ihlpe.ATT.COM> <998@mit-caf.UUCP>
Reply-To: markhall@pyramid.UUCP (Mark Hall)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 29

In article <998@mit-caf.UUCP> vlcek@mit-caf.UUCP (Jim Vlcek) writes:

>I am under the impression that there is nothing wrong with having an
>``extern'' reference *and* a variable definition in the source file,
>and in fact I have done so in all of my C programming.  
>-- 
>Jim Vlcek
>vlcek@caf.mit.edu
>!{ihnp4,harvard,seismo,rutgers}!mit-eddie!mit-caf!vlcek

Your practice is OK according to K&R, pg 77:

	There must be only one `definition' of an external variable among
	all the files that make up the source program; other files may
	contain EXTERN declarations to access it.  (There may also
	be an EXTERN declaration in the file containing the definition).

On a related note, it's funny to watch how different compilers react to:
	main() {
		register int a;
		extern   int a;
	}
Some ignore the register directive and map `a' to some global variable
of the same name.  Others ignore the extern directive and create
local references to `a'.  I never could find out from K&R if this was 
an error, or if the `extern' should be ignored, or what.  Can anyone 
comment?  Just the facts, please.

-Mark Hall