Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!purdue!decwrl!megatest!djones
From: djones@megatest.UUCP (Dave Jones)
Newsgroups: comp.lang.c
Subject: Re: A solution to the multiple inclusion problem
Message-ID: <8956@goofy.megatest.UUCP>
Date: 25 Oct 89 00:39:27 GMT
References: <946@friar-taac.UUCP>
Distribution: comp
Organization: Megatest Corporation, San Jose, Ca
Lines: 27

From article <946@friar-taac.UUCP), by matthew@sunpix.UUCP ( Sun Visualization Products):
) In article <15316@bloom-beacon.MIT.EDU) tada@athena.mit.edu (Michael J Zehr) writes:
))In article <14240@well.UUCP) nagle@well.UUCP (John Nagle) writes:
)))[problem of multiple exclusion, generally solved by:]
)))	#ifndef XXX
)))	#define XXX
)))	...content...
)))	#endif
)))This works, but on the second inclusion, the file still has to be read and
)))parsed ... 

I think you'll live a happier, more productive life, if you do it
this way...


	#ifndef XXX
	...content...
	#define XXX
	#endif


It makes no difference where you put the #define, unless you have
files which define recursive data-structures and thus potentially
refer to each other. (You use "struct foo*" before "struct foo" is
actually defined.) If it gets screwed up, and each file includes the
other, and if the the #define is at the top, trying to figure out what went
wrong can make your life a living hell.