Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:54242
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.220.170 as permitted sender)
MIME-Version: 1.0
Sender: laruence@gmail.com
In-Reply-To: <4E31A872.5030608@gmail.com>
References: <CABBJUpc_r1XftvPVfpQcZ_EzbYiV+-kKjdqQArUm0H6UGN2wTQ@mail.gmail.com>
	<4E31A872.5030608@gmail.com>
Date: Fri, 29 Jul 2011 09:08:32 +0800
Message-ID: <CABBJUpd14p7mL+jC+A+EjBE2zxin2hd+c2m7Jx5=VooQqdXcjw@mail.gmail.com>
To: =?UTF-8?B?w4FuZ2VsIEdvbnrDoWxleg==?= <keisial@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] [RFC]strn(case)cmp supporting negative length as third parameter
From: laruence@php.net (Laruence)

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 =C3=81ngel Gonz=C3=A1lez <keisial@gmail.com>:
> Laruence wrote:
>>
>> Hi:
>>
>> =C2=A0 strn(case)cmp dosen't =C2=A0support a negative length as its thir=
d
>> paramter, =C2=A0while substr dose.
>
>> =C2=A0here is the rfc: https://wiki.php.net/rfc/strncmpnegativelen
>>
>> =C2=A0any question? plz worte me back.
>>
>> =C2=A0thanks
>
> 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 firs=
t
>> two parameters, then strn(case)cmp will work as strncmp in the reverse o=
rder
>> with the abs value:
>
> Looking at
>>
>> var_dump =C2=A0<http://www.php.net/var_dump>(strncmp
>> =C2=A0<http://www.php.net/strncmp>("prefix_num", =C2=A0"num", =C2=A0-10)=
);
>> =C2=A0 //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 =C2=A0<http://www.php.net/var_dump>(strncmp
>> =C2=A0<http://www.php.net/strncmp>("prefix_num", =C2=A0"num", =C2=A0-3))=
;
>
> Seems an implementation bug.
>
>



--=20
Laruence =C2=A0Xinchen Hui
http://www.laruence.com/