Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!bloom-beacon!adam.pika.mit.edu!scs
From: scs@adam.pika.mit.edu (Steve Summit)
Newsgroups: comp.lang.c
Subject: null if statements
Message-ID: <12685@bloom-beacon.MIT.EDU>
Date: 15 Jul 89 00:27:20 GMT
References: <713@srhqla.SR.COM>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: scs@adam.pika.mit.edu (Steve Summit)
Lines: 31

in article <713@srhqla.SR.COM>, tcm@srhqla.SR.COM (Tim Meighan) writes:
> 1. There is rarely, if ever, a case when it would be reasonable for a
>    program to contain an if() statement that, when evaluated as true,
>    does absolutely nothing.  (In other words, simply fall through to
>    the code to be executed when the if() is false.)

Just yesterday I discovered, to my considerable astonishment, a
good use for an if statement which always evaluates as false, and
does nothing:

	if(0)
		;
#ifdef onething
	else if(Streq(command, "agitate"))
		agitate();
#endif
#ifdef anotherthing
	else if(Streq(command, "blend"))
		blend();
#endif
#ifdef yetanotherthing
	else if(Streq(command, "churn"))
		churn();
#endif
	else	fprintf(stderr, "unknown command \"%s\"\n", command);

The first, empty if keeps the code syntactically correct
regardless of which of the "real" branches are #ifdeffed out.

                                            Steve Summit
                                            scs@adam.pika.mit.edu