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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: const * question
Message-ID: <6578@brl-smoke.ARPA>
Date: Mon, 19-Oct-87 08:31:13 EDT
Article-I.D.: brl-smok.6578
Posted: Mon Oct 19 08:31:13 1987
Date-Received: Tue, 20-Oct-87 02:06:31 EDT
References: <1151@lznv.ATT.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 22
Keywords: const pointer

In article <1151@lznv.ATT.COM> psc@lznv.ATT.COM (Paul S. R. Chisholm) writes:
>char *
>next( const char *s )
>{
>	const char	*p;
>	p = s + 1;
>	return p;
>}
>Here's the rub:  my compiler (Turbo C) complains that the return
>statement is a suspicious pointer conversion.

It IS "suspicious", but not necessarily erroneous, depending on
what s actually pointed to and what you will subsequently do with
p.  I recommend writing
	p = (char *)s + 1;
to indicate that you know about the constness and are deliberately
ignoring it.

All that const on a formal function parameter means is that the
function itself shall not use that pointer to modify data, not
that the data pointed to is necessarily non-modifiable.  This is
a subtle but important distinction.