Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!pt.cs.cmu.edu!k.gp.cs.cmu.edu!dandb
From: dandb@k.gp.cs.cmu.edu (Dean Rubine)
Newsgroups: comp.lang.c
Subject: Re: use of if (!cptr) and if (cptr), where cptr is a *)
Keywords: really about using the comma operator
Message-ID: <5630@pt.cs.cmu.edu>
Date: 25 Jul 89 06:11:17 GMT
References: <10099@mpx2.mpx.com> <93@microsoft.UUCP> <10100@mpx2.mpx.com> <10562@smoke.BRL.MIL> <1989Jul24.194646.3012@nc386.uucp>
Organization: Carnegie-Mellon University, CS/RI
Lines: 33

A slightly better use of a comma in a while expression is:

	while(printf("? "), gets(line) != NULL) {
		... whatever ...
	}

I think it beats the alternatives:
	
	for(;;) {
		printf("? ");
		if(gets(line) == NULL)
			break;
		... whatever ...
	}

	       -- or --

	for(printf("? "); gets(line) != NULL; printf("? ")) {
		... whatever ...
	}
	

I also occasionally use the comma to save braces:

	if((f = fopen(file, "r")) == NULL)
		fprintf(stderr, "Can't open %s\n", file), exit(2);


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