NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/std/c/518

Internet Message Format | 1996-08-06 | 2.0 KB

Path: solon.com!not-for-mail
From: [e-mail] (Lawrence Kirby)
Newsgroups: comp.lang.c.moderated,comp.std.c
Subject: Behaviour of mem functions when n=0 ?
Date: 6 Mar 1996 18:28:45 -0600
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In article <4hgc3d$[e-mail]>
           [e-mail] "Larry Jones" writes:

 > In article <4hdqn5$[e-mail]>, [e-mail]
 > (Lawrence Kirby) writes about memcmp et al. with n==0:
 > > Probably. However the result is defined by some rather unfortunate wording in
 > > the standard:
 >
 > The intent of the standard has been clarified by a Technical Corrigendum
 > which adds the following text to the introductory matter in 7.11.1
 > String Function Conventions:
 >
 >         Where an argument declared as |size_t n| specifies the length of
 >         the array for a function, |n| can have the value zero on a call
 >         to that function.  Unless explicitly stated otherwise in the
 >         description of a particular function in this subclause, pointer
 >         arguments on such a call must still have valid values, as
 >         described in subclause 7.1.7.  On such a call, a function that
 >         locates a character finds no occurrence, a function that
 >         compares two character sequences returns zero, and a function
 >         that copies characters copies zero characters.
 >
 > Note that this applies to the strn* functions as well as the mem*
 > functions.

That does pretty much clear it up. However the wording for the individual
functions is still nonsensical and it would have been better if that had
been fixed.

--
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Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
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