Path: utzoo!attcan!uunet!mcsun!ukc!tcdcs!swift.cs.tcd.ie!maths.tcd.ie!tim
From: tim@maths.tcd.ie (Timothy Murphy)
Newsgroups: comp.std.c
Subject: memcpy
Summary: memcpy -- differences in interpretation
Keywords: memcpy
Message-ID: <1990Sep19.021418.11574@maths.tcd.ie>
Date: 19 Sep 90 02:14:18 GMT
Organization: Dept. of Maths, Trinity College, Dublin, Ireland.
Lines: 21

Recently, while debugging the Unix version of unzip.c,
I found a surprising discrepancy between 'memcpy' on various machines.

In unzip.c it is assumed that the effect of
	buf[0] = c;
	memcpy(buf+1, buf, 20);
is to set
	buf[0] = buf[1] = buf[2] = ... = buf[21] = c.

This is indeed the effect with most compilers I tried --
rather surprisingly, to me --
but not with cc on the Sun SparcStation (sun4).

Is this a bug on the Sparc,
or is memcpy not fully specified?

-- 

Timothy Murphy  

e-mail: tim@maths.tcd.ie