Article View: comp.std.c
Article #853Re: null pointers [joke?] (was: commom malloc/free practice ...)
From: Joe English
Date: Fri, 27 Oct 1989 17:22
Date: Fri, 27 Oct 1989 17:22
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1354 bytes
bdm659@csc.anu.oz writes: > Section 3.2.2.3 (on the result of casting 0 to a pointer type): > > "Such a pointer, called a null pointer, is guaranteed not to > point to any object or function." > > Section 3.3.9 (on pointer equality): > > "If two pointers to object or incomplete types compare equal, > they point to the same object." > >From these two rules, it logically follows that (int*)0 != (int*)0 . Not really; 3.3.9 says (loosely translated) [(A and B point to an object) and (A == B)] ==> [it is the same object]. (1) (2) (3) If (1) is false it does not follow that (2) is false. --Joe English jeenglis@nunki.usc.edu
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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!iuvax!cica!ctrsol!gem.mps.ohio-state.edu!apple!usc!merlin.usc.edu!nunki.usc.edu!jeenglis From: jeenglis@nunki.usc.edu (Joe English) Newsgroups: comp.std.c Subject: Re: null pointers [joke?] (was: commom malloc/free practice ...) Message-ID: <6054@merlin.usc.edu> Date: 27 Oct 89 17:22:11 GMT References: <11380@smoke.BRL.MIL> <8952@goofy.megatest.UUCP> <872.254895b5@csc.anu.oz> Sender: news@merlin.usc.edu Reply-To: jeenglis@nunki.usc.edu (Joe English) Organization: University of Southern California, Los Angeles, CA Lines: 25