» strpos(), substr() oder str[0] . str[1] um Stringvorkommen zu prüfen?

<?php
$str = 'foobar';

$start_time = microtime(true);
for ($i = 0; $i < 1000000; $i++) {
	if ($url[0] == 'f' && $url[1] == 'o' && $url[2] == 'o') {
		// starts with foo
	}
}
echo (microtime(true) - $start_time) . PHP_EOL;

$start_time = microtime(true);
for ($i = 0; $i < 1000000; $i++) {
	if ($url[0] . $url[1] . $url[2] == 'foo') {
		// starts with foo
	}
}
echo (microtime(true) - $start_time) . PHP_EOL;

$start_time = microtime(true);
for ($i = 0; $i < 1000000; $i++) {
	if (substr($url, 0, 2) == 'foo') {
		// starts with foo
	}
}
echo (microtime(true) - $start_time) . PHP_EOL;

$start_time = microtime(true);
for ($i = 0; $i < 1000000; $i++) {
	if (strpos($url, 'foo') === 0) {
		// starts with foo
	}
}
echo (microtime(true) - $start_time) . PHP_EOL;
// results:
// 0.22709417343140 access by offset
// 0.67710185050964 concat
// 0.37688708305359 substr()
// 0.37025094032288 strpos()
?>

Mach mit!