str_replace vs preg_replace

转自：http://benchmarks.ro/2011/02/str_replace-vs-preg_replace/

事实证明str_replace确实比preg_replace快。

If you find yourself handling strings and replacing sub-strings within them you want to make sure that you are using the fastest way possible to do it.
In order to help you we ran tests using an average length string (50k characters) and 100*1000 test runs.
After running these tests we concluded that str_replace is faster thanpreg_replace when it comes to simple replace rules, these being our results for two separate full test runs:

Time for str_replace: 2.2866821289062 seconds
Time for preg_replace: 2.9614992141724 seconds

Time for str_replace: 2.471617937088 seconds
Time for preg_replace: 3.2965259552002 seconds

You can see the code we used for benchmarking below:

<?php

//Build string to be used
$max_elements=50000; $max_runs=100;

$test_string='';
for($i=0;$i<$max_elements;$i++)    $test_string.=chr(rand(32,127));

function test_str_replace()
{
global $test_string,$max_runs;
for($i=0;$i<$max_runs;$i++)    $test_string=str_replace(' ',' ',$test_string);
}

function test_preg_replace()
{
global $test_string,$max_runs;
for($i=0;$i<$max_runs;$i++)    $test_string=preg_replace("/[ ]/",' ',$test_string);
}

$time = microtime(true);
for($i=0;$i<$max_runs;$i++) test_str_replace();
$time = microtime(true) - $time;
echo "Time for str_replace: {$time} seconds<br>\n";

$time = microtime(true);
for($i=0;$i<$max_runs;$i++) test_preg_replace();
$time = microtime(true) - $time;
echo "Time for preg_replace: {$time} seconds<br>\n";

?>