Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!haven!ncifcrf!nlm-mcs!adm!smoke!gwyn
From: gwyn@smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: memcpy vs. memmove (was: Re: Explanation, please!)
Message-ID: <8482@smoke.ARPA>
Date: 13 Sep 88 13:40:47 GMT
References: <8389@smoke.ARPA> <7039@bloom-beacon.MIT.EDU>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 12

In article <7039@bloom-beacon.MIT.EDU> scs@adam.pika.mit.edu (Steve Summit) writes:
>I'll probably be disgusted by the answer, but can someone explain
>why two functions are needed instead of one?  Why not just add
>the guarantee to memcpy?

(1) many people want a fast block-move, many want one that does the
"correct" thing on overlaps.  Two routines allows the application to
choose the trade-off.  A vendor could choose to make memcpy just
another entry point for memmove.

(2) it's possible that some existing (nonportable) applications depend
on the specific implementation of their current memcpy().