On Mon, Oct 08, 2007 at 01:45:27AM +0000, Miles Bader wrote:
> Alex Riesen <raa.lkml@xxxxxxxxx> 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;
Won't work because ->len are size_t and return value is int, so on 64
bits platform, this has chances to overflow.
FWIW I believe we are doing micro-benchs in a function that is used in
2 places in git right now.
--
·O· Pierre Habouzit
··O madcoder@xxxxxxxxxx
OOO http://www.madism.org
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