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

[Jeremiah Mahler <jmmahler@gmail.com>]

Torsten,

On Tue, Jun 17, 2014 at 10:23:14AM +0200, Torsten Bögershausen wrote:
> 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)
> 
Yes, "minimum" doesn't make sense.  "common length" sounds better.

> > strings are identical up to this minimum common length, the length
> > difference is returned.
> > 
> > Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
> > ---
> >  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.
> 
Don't need negatives, size_t is more appropriate.  Fixed.

> 
> > +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);
> > +}

Thanks,
-- 
Jeremiah Mahler
jmmahler@gmail.com
http://github.com/jmahler