strlen scans the string; strrchr also scans the string.
On 2020-07-01 10:23, Martin Lewis wrote:
Hi,
I'm not sure what I'm missing, from a quick glance at strrchr
(glibc's) it seems that it scans the string only once?
Thank you,
Martin
On Tue, 30 Jun 2020 at 01:34, Denys Vlasenko <vda.li...@googlemail.com
<mailto:vda.li...@googlemail.com>> wrote:
This scans the string twice, unnecessarily. Let's not do that.
On Thu, Jun 11, 2020 at 3:45 PM Martin Lewis
<martin.lewis....@gmail.com <mailto:martin.lewis....@gmail.com>>
wrote:
>
> function old new
delta
> last_char_is 53 30
-23
>
------------------------------------------------------------------------------
> (add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-23) Total:
-23 bytes
> text data bss dec hex filename
> 981322 16915 1872 1000109 f42ad busybox_old
> 981299 16915 1872 1000086 f4296 busybox_unstripped
>
> Signed-off-by: Martin Lewis <martin.lewis....@gmail.com
<mailto:martin.lewis....@gmail.com>>
> ---
> libbb/last_char_is.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/libbb/last_char_is.c b/libbb/last_char_is.c
> index 66f2e3635..1fff08f9f 100644
> --- a/libbb/last_char_is.c
> +++ b/libbb/last_char_is.c
> @@ -13,11 +13,10 @@
> */
> char* FAST_FUNC last_char_is(const char *s, int c)
> {
> - if (s && *s) {
> - size_t sz = strlen(s) - 1;
> - s += sz;
> - if ( (unsigned char)*s == c)
> - return (char*)s;
> + if (s) {
> + char *index = strrchr(s, c);
> + if (index && *(index + 1) == '\0')
> + return index;
> }
> return NULL;
> }
> --
> 2.11.0
>
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