matching a list of prefixes, preg_match is of course also more flexible, but it seems like its also going to be faster in many cases

gistfile1.txt

<?php

$iterations = 10000;

$url = '/foo/bar';
$list1 = array('/bar', '/ding', 'dong');
$list2 = array('/foo', '/bar', '/ding', 'dong');
$regexp1 = '/^\/(bar|ding|dong)/';
$regexp2 = '/^\/(bar|foo|ding|dong)/';

function match_strpos($url, $list, $iterations) {
    for ($i = 0; $i < $iterations; $i++) {
        foreach ($list as $item) {
            if (0 === strpos($url, $item)) {
                break;
            }
        }
    }
}

function match_regexp($url, $regexp, $iterations) {
    for ($i = 0; $i < $iterations; $i++) {
        preg_match($regexp, $url);
    }
}

$times['init'] = microtime(true);
match_strpos($url, $list1, $iterations);
$times['strpos()/no match    '] = microtime(true);
match_regexp($url, $regexp1, $iterations);
$times['preg_match()/no match'] = microtime(true);
match_strpos($url, $list2, $iterations);
$times['strpos()/match       '] = microtime(true);
match_regexp($url, $regexp2, $iterations);
$times['preg_match()/match   '] = microtime(true);

$previous_time = array_shift($times);
foreach ($times as $key => $time) {
    echo("$key: ".($time - $previous_time))."\n";
    $previous_time = $time;
}

/*
results without xdebug.so loaded:
strpos()/no match    : 0.041649103164673
preg_match()/no match: 0.014512062072754
strpos()/match       : 0.016393899917603
preg_match()/match   : 0.015846014022827
 */