Path: utzoo!attcan!uunet!wash08!rae98 From: rae98@wash08.UUCP (Robert A. Earl) Newsgroups: comp.lang.c Subject: Re: "do ... while ((NULL + 1) - 1);" -- valid C? Message-ID: <625@wash08.UUCP> Date: 10 Aug 89 13:27:17 GMT References: <1043@levels.sait.edu.au> <961@virtech.UUCP> <10684@smoke.BRL.MIL> <696@ftp.COM> Reply-To: rae98@wash08.UUCP (Robert A. Earl) Organization: American Chemical Society, Washington, DC Lines: 22 In article <696@ftp.COM> wjr@ftp.UUCP (Bill Rust) writes: >In article <10684@smoke.BRL.MIL> gwyn@brl.arpa (Doug Gwyn) writes: >>In article <961@virtech.UUCP> cpcahil@virtech.UUCP (Conor P. Cahill) writes: >>>NULL + 1 is a valid operations, ... >>No! >In my experience, NULL is always defined using the preprocessor line >"#define NULL 0" (or 0L). Since the while construct is relying on the >fact NULL is, in fact, 0, doing NULL + 1 - 1 is ok. >Bill Rust (wjr@ftp.com) I have to disagree with Bill here. The NULL being returned was from a string manipulation function...ie not just a NULL but a (char *) NULL....I believe it is illegal (or at least unportable) to add (char *)NULL + 1. -- =========================================================== Name: Bob Earl Phone: (202) 872-6018 (wk) UUCP: ...!uunet!wash08!rae98 BITNET: ...rae98@CAS (At least, that is what I'm told)