Edit report at https://bugs.php.net/bug.php?id=62648&edit=1
ID: 62648
Comment by: carloschilazo at gmail dot com
Reported by: normadize at gmail dot com
Summary: similar_text() returns wrong values
Status: Open
Type: Bug
Package: Strings related
Operating System: Linux, Win32
PHP Version: 5.3.15
Block user comment: N
Private report: N
New Comment:
the only thing that I'd want to clear out first about this, is the performance
of
your algorithm vs the built-in function.
Could you please provide the test case you are using to measure this?
Thanks!
Previous Comments:
------------------------------------------------------------------------
[2012-07-29 05:48:14] normadize at gmail dot com
Note that besides giving different results when swapping arguments, it gives
wrong results sometimes completely. Here's an example:
<?php
$s1 = 'biocompatibilitystudiesofironoxidedextrinthinfilmsbacdetundgakslfnnd';
$s2 =
'studyofironoxidenanoparticlescoatedwithdextrinobtainedbybcgagsfddteuhdgavdjfkdbey';
echo similar_text($s1, $s2);
echo ",";
echo similar_text($s2, $s1);
?>
Gives 34,32 instead of 35,35.
Longest common substring is "studofironoxidedextrintinbcdtudgafd" which is 35
chars long.
I have written a small custom PHP extension that I compile and load in all my
PHP deployments for speed because a PHP implementation of the longest common
substring algorithm in PHP is painfully slow. My extension is based on suffix
trees rather than recursive calls, which is generally faster for short to
moderately long strings.
Isn't any dev interested in fixing this very useful function? It's been such a
long time ...
I can post my extension code and will attempt to patch the original
similar_text() too.
------------------------------------------------------------------------
[2012-07-24 06:17:33] normadize at gmail dot com
Description:
------------
similar_text() returns wrong values, see below for reproducible error.
This is actually a very old bug ... would be nice if someone finally fixed it.
Test script:
---------------
echo similar_text("test","wert");
echo "|";
echo similar_text("wert","test");
Expected result:
----------------
2|2
Actual result:
--------------
1|2
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=62648&edit=1
