From: Miles Bader <miles@gnu.org>
Date: Mon, 08 Oct 2007 01:45:27 GMT
Subject: Re: [PATCH] Make strbuf_cmp inline, constify its arguments and optimize it a bit
Message-ID: <87odfapefc.fsf@catnip.gol.com>
In-Reply-To: <20071007223140.GG2765@steel.home>

Alex Riesen <raa.lkml@gmail.com> writes:
> int strbuf_cmp2(struct strbuf *a, struct strbuf *b)
> {
> 	int len = a->len < b->len ? a->len: b->len;
> 	int cmp = memcmp(a->buf, b->buf, len);
> 	if (cmp)
> 		return cmp;
> 	return a->len < b->len ? -1: a->len != b->len;
> }

BTW, why are you making such effort to return only -1, 0, or 1 in the
last line?  memcmp/strcmp make no such guarantee; e.g. glibc says:

     The `strcmp' function compares the string S1 against S2, returning
     a value that has the same sign as the difference between the first
     differing pair of characters (interpreted as `unsigned char'
     objects, then promoted to `int').

     If the two strings are equal, `strcmp' returns `0'.

     A consequence of the ordering used by `strcmp' is that if S1 is an
     initial substring of S2, then S1 is considered to be "less than"
     S2.

So I think the last line can just be:

   return a->len - b->len;

-miles

-- 
Suburbia: where they tear out the trees and then name streets after them.