From -1046506715272375968 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 1149ec,c0f8f764e8b7d30f X-Google-Attributes: gid1149ec,public X-Google-Thread: f78e5,c0f8f764e8b7d30f X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1992-12-19 15:59:34 PST Xref: sparky comp.std.c++:1839 comp.std.c:3233 Newsgroups: comp.std.c++,comp.std.c Path: sparky!uunet!spool.mu.edu!uwm.edu!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!deccrl!news.crl.dec.com!news!nntpd.lkg.dec.com!jit345.bad.jit.dec.com!diamond From: diamond@jit345.bad.jit.dec.com (Norman Diamond) Subject: Re: Question about sizeof in C/C++. Message-ID: <1992Dec18.021610.24482@nntpd.lkg.dec.com> Sender: usenet@nntpd.lkg.dec.com (USENET News System) Reply-To: diamond@jit.dec.com (Norman Diamond) Organization: Digital Equipment Corporation Japan , Tokyo References: Date: Fri, 18 Dec 1992 02:16:10 GMT Lines: 23 In article amf@amfent.Gwinnett.COM (Andy Feibus) writes: >jamesc@swapsdev.state.state.COM.AU (James Cribb) writes: >> Given >> struct Something* ps; >> unsigned k; >> do the C or C++ standards guarantee that >> &ps[k] == ((char*) ps) + k * sizeof(struct Something) >Assuming that you [cm]alloc enough memory for ps to support accessing the >k'th element of it, the answer is... no. He was asking about the standards, for which (under the condition you state) the answer is... yes. >Different compilers see &ps[k] differently; use parentheses to clarify: > &(ps[k]). Even K&R-1 and Stroustrop-1 prohibited seeing this expression differently. Parenthesization is nice for human readers so that we don't have to look it up all the time, but not necessary for C or C++ compilers. -- Norman Diamond diamond@jit081.enet.dec.com If this were the company's opinion, I wouldn't be allowed to post it. "It's been a lovely recession."