Path: utzoo!mnetor!motto!dave
From: dave@motto.UUCP (David Brown)
Newsgroups: comp.lang.c
Subject: Re: strncpy
Message-ID: <80@motto.UUCP>
Date: 24 Jan 90 14:25:19 GMT
References: <e-mail_to_poser> <11527@csli.Stanford.EDU> <000003Q@cdis-1.UUCP> <11616@csli.Stanford.EDU> <48314938.f69e@phobos.UUCP> <11864@csli.Stanford.EDU> <25BC3A32.3F5B@marob.masa.com> <11881@csli.Stanford.EDU> <4128@helios.TAMU.EDU>
Reply-To: dave@motto.UUCP (David Brown)
Lines: 25

In article <4128@helios.TAMU.EDU> john@stat.tamu.edu (John S. Price) writes:
>Every manual I read says this:
>"... If the string pointed to by the source has fewer than count
>characters, nulls are added to the end of dest until count characters 
>have been copied." -- C - The Complete Reference.
>
>"... strncpy(s,t,n)    copy exactly n characters; null pad if necessary"
> -- Unix Programming Environment
>

We found this useful when dealing with the keys of ISAM files under VMS.
If the key was a C string, we used strncpy() to copy it rather than
strcpy().  This guaranteed that the bytes following the '\0' were all
zeroes.  This was important because the filesystem compared all bytes of
the key.

If we had used strcpy(), two keys which were the same string value could
be different as far as the filesystem was concerned, because of garbage
following the '\0'.

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