[RFC]strn(case)cmp supporting negative length as third parameter

Hi:

why?

I think this change would not cause any other side-effects.

and if you are worry about INT_MAX, I think it's ok to declare with
long(in fact, I already did so).

thanks

2011/7/28 Derick Rethans derick@php.net:

Hi:

  strn(case)cmp dosen't  support a negative length as its third
paramter,  while substr dose.

 I wrote a patch to make strn(case)cmp supporting negative length,
make following script works as expect:

    <?php
   if (strncmp("prefix_num", "num", -3) === 0) {
        echo "they have same suffix\n";
   }
  ?>

 here is the rfc: https://wiki.php.net/rfc/strncmpnegativelen

• You're changing binary API of some API functions, so this can't go
   into PHP 5.3:

       -ZEND_API int zend_binary_strncmp(const char *s1, uint len1, const char *s2, uint len2, uint length);
       +ZEND_API int zend_binary_strncmp(const char *s1, uint len1, const char *s2, uint len2, int length);

cheers,
Derick

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Laruence  Xinchen Hui
http://www.laruence.com/

Hi:
first of all, yes , you are right about the reverse order thing:

and then, they are not equal:

<?php
echo "strncmp:\n";
var_dump(strncmp("laruence", "nce", -10));
var_dump(strncmp("ecneural", "ecn", 10));

var_dump(strncmp("ecneural", "ecn", 3));
var_dump(strncmp("laruence", "nce", -3));
?>

will output:
strncmp:
int(5)
int(5)
int(0)
int(0)

thanks

2011/7/29 Ángel González keisial@gmail.com:

Laruence wrote:

Hi:

  strn(case)cmp dosen't  support a negative length as its third
paramter,  while substr dose.

 here is the rfc: https://wiki.php.net/rfc/strncmpnegativelen

 any question? plz worte me back.

 thanks

What do you exactly mean by "in the reverse order" in

if the abs of the negative length is greater than any strlen of the first
two parameters, then strn(case)cmp will work as strncmp in the reverse order
with the abs value:

Looking at

var_dump  http://www.php.net/var_dump(strncmp
 http://www.php.net/strncmp("prefix_num",  "num",  -10));
  //outpu: int(7)

it seems to mean that it would be equivalent to

var_dump(strncmp("mun_xiferp", "mun", 10));

However, if I'm reading the patch correctly, it would
be taking the smaller string. Ie. it would be equivalent
to

var_dump  http://www.php.net/var_dump(strncmp
 http://www.php.net/strncmp("prefix_num",  "num",  -3));

Seems an implementation bug.

--
Laruence  Xinchen Hui
http://www.laruence.com/