Subject: Re: [PATCH v2 1/3] add strnncmp() function

From: Torsten Bögershausen <[email-masked]>
Date: Tue, 17 Jun 2014 10:23:14 +0200

On 2014-06-17 09.34, Jeremiah Mahler wrote:
> Add a strnncmp() function which behaves like strncmp() except it takes
> the length of both strings instead of just one.  It behaves the same as
> strncmp() up to the minimum common length between the strings.  When the
minimum common length? Isn'n t that 0?
Using the word "common", I think we could call it "common length".
(And more places below)

> strings are identical up to this minimum common length, the length
> difference is returned.
> 
> Signed-off-by: Jeremiah Mahler <[email-masked]>
> ---
>  strbuf.c | 9 +++++++++
>  strbuf.h | 2 ++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/strbuf.c b/strbuf.c
> index ac62982..4eb7954 100644
> --- a/strbuf.c
> +++ b/strbuf.c
> @@ -600,3 +600,12 @@ char *xstrdup_tolower(const char *string)
>  	result[i] = '\0';
>  	return result;
>  }
> +
strncmp uses size_t, not int:
int strncmp(const char *s1, const char *s2, size_t n);

Is there a special reason to allow negative string length?
Some call sites use int when calling strncmp() or others,
that is one thing.
But when writing a generic strnncmp() function, I think
it should use size_t, unless negative values have a meaning and
are handled in the code.

> +int strnncmp(const char *a, int len_a, const char *b, int len_b)
> +{
> +	int min_len = (len_a < len_b) ? len_a : len_b;
> +	int cmp = strncmp(a, b, min_len);

> +	if (cmp)
> +		return cmp;
> +	return (len_a - len_b);
> +}