Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!mailrus!ukma!husc6!spdcc!ftp!wjr From: wjr@ftp.COM (Bill Rust) Newsgroups: comp.lang.c Subject: Re: "do ... while ((NULL + 1) - 1);" -- valid C? Message-ID: <696@ftp.COM> Date: 9 Aug 89 13:38:08 GMT References: <1043@levels.sait.edu.au> <961@virtech.UUCP> <10684@smoke.BRL.MIL> Reply-To: wjr@ftp.UUCP (Bill Rust) Organization: FTP Software, Inc. Lines: 15 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. I certainly wouldn't recommend using it as a reference to memory. But, unless NULL is a reserved word to your compiler, the compiler sees 0 + 1 - 1 and that is ok. Bill Rust (wjr@ftp.com)