Edit report at https://bugs.php.net/bug.php?id=63893&edit=1
ID: 63893
Updated by: cataphr...@php.net
Reported by: scope at planetavent dot de
Summary: poor efficiency of strtr() using array with keys of
very different length
Status: Assigned
Type: Bug
Package: Strings related
Operating System: Windows Server 2008 / RHEL 6.3
PHP Version: 5.4.10
Assigned To: cataphract
Block user comment: N
Private report: N
New Comment:
My patch so far:
https://github.com/cataphract/php-src/compare/strtr
Previous Comments:
------------------------------------------------------------------------
[2013-01-03 14:34:36] scope at planetavent dot de
Description:
------------
As the documentation of strtr() points out, strtr "... will be the most
efficient when all the keys have the same size".
Using keys of very different lengths results in poor performance, even on very
small inputs.
If the str_repeat() for "m" in the test script is adjusted to 20000 the
resulting runtime increases to 45 seconds for strtr() while str_replace() does
not increase notably.
There are cases where the replacement array is built dynamically, so there
might be little control over the keylengths. It's easy to expand the example
such that strtr() takes several hours compared to just a few seconds using
str_replace().
Test script:
---------------
<?php
$text = str_repeat( 'm', 2000 );
$long_from_a = str_repeat( 'a', 1 );
$long_from_x = str_repeat( 'x', 1500 );
$replacements = array(
$long_from_a => 'b',
$long_from_x => 'y'
);
$start = microtime( true );
$result_1 = strtr( $text, $replacements );
echo "strtr: " . number_format( microtime( true ) - $start, 4 ) . "\n";
$start = microtime( true );
$result_2 = str_replace( array_keys( $replacements ), array_values(
$replacements ), $text );
echo "str_replace: " . number_format( microtime( true ) - $start, 4 ) . "\n";
echo $result_1 === $result_2 ? "results match!\n": "no match!\n";
Expected result:
----------------
strtr: 0.0001
str_replace: 0.0001
results match!
Actual result:
--------------
strtr: 2.4203
str_replace: 0.0001
results match!
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=63893&edit=1
