Article View: comp.std.c++
Article #1217Re: Zero-length structures and pointer comparisons
From: John MAX Skaller
Date: Sat, 12 Dec 1992 15:54
Date: Sat, 12 Dec 1992 15:54
28 lines
1693 bytes
1693 bytes
In article <1992Dec9.133956.29659@lth.se> dag@seldon.control.lth.se (Dag Bruck) writes:
>In <comp.std.c++> fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON) writes:
>>
>>What I propose is that we define a *standard library function* which computes
>>a total ordering on pointers.
>>
>>int compare_pointers(const void *, const void *);
>> /* Returns negative, zero, or positive in the same manner as strcmp().
>> Perhaps in the interests of tradition and unreadability it should
>> be called ptrcmp() instead of compare_pointers() :-) */
>
>Suggested semantics: for any pointers p and q:
>
> p == q <=> ptrcmp(p,q) == 0
Are you SURE you need this? Why should == and ptrcmp
be in any way related? In particular, on the 8086 if
ptrcmp was a bitwise compare it would yield a total order,
but we would have
p == q && ptrcmp(p,q) !=0
--
;----------------------------------------------------------------------
JOHN (MAX) SKALLER, maxtal@extro.ucc.su.oz.au
Maxtal Pty Ltd, 6 MacKay St ASHFIELD, NSW 2131, AUSTRALIA
;--------------- SCIENTIFIC AND ENGINEERING SOFTWARE ------------------
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Newsgroups: comp.std.c++ Path: arc1-ca.pugleaf.net!sparky!uunet!munnari.oz.au!metro!extro.ucc.su.OZ.AU!maxtal From: maxtal@extro.ucc.su.OZ.AU (John MAX Skaller) Subject: Re: Zero-length structures and pointer comparisons Message-ID: <1992Dec12.155417.2628@ucc.su.OZ.AU> Sender: news@ucc.su.OZ.AU Nntp-Posting-Host: extro.ucc.su.oz.au Organization: MAXTAL P/L C/- University Computing Centre, Sydney References: <1992Dec8.103218.27689@lth.se> <9234423.15066@mulga.cs.mu.OZ.AU> <1992Dec9.133956.29659@lth.se> Date: Sat, 12 Dec 1992 15:54:17 GMT Lines: 28