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From: rgenter@BBN-LABS-B.ARPA (Rick Genter)
Newsgroups: net.lang.c
Subject: Re: microsoft C considered stupid
Message-ID: <1586@brl-smoke.ARPA>
Date: Mon, 23-Jun-86 10:11:12 EDT
Article-I.D.: brl-smok.1586
Posted: Mon Jun 23 10:11:12 1986
Date-Received: Wed, 25-Jun-86 05:21:41 EDT
Sender: news@brl-smoke.ARPA
Lines: 37


     Actually, the defined() preprocessor function does provide a convenience
over #ifdef in one specific case:

	#if defined(VAX730) || defined (VAX750) || defined (VAX780)
		< code which is included when any of the three symbols
		  are defined >
	#endif /* defined ... */

This is a royal pain to accomplish with #ifdef:

	#undef KLUDGE
	#ifdef VAX730
	#define KLUDGE
	#endif /* def VAX730 */

	#ifdef VAX750
	#define KLUDGE
	#endif /* def VAX750 */

	#ifdef VAX780
	#define KLUDGE
	#endif /* def VAX780 */

	#ifdef KLUDGE
		< code which is included when any of the three symbols
		  are defined >
	#endif /* def KLUDGE */

Alternatively, you have to include the code three times.

					- Rick
--------
Rick Genter 				BBN Laboratories Inc.
(617) 497-3848				10 Moulton St.  6/506
rgenter@labs-b.bbn.COM  (Internet new)	Cambridge, MA   02238
rgenter@bbn-labs-b.ARPA (Internet old)	linus!rgenter%BBN-LABS-B.ARPA (UUCP)