substr or strlen - Which offers the best performance? PHP

Question

I need to run a check on multiple variables, some of which will be urls and others will only contain no more than 5 or 6 characters, none of which will ever be "http".

Which of the two methods below gives the best performance in terms of speed and processor load.

$str = 'http://somereallylongwebaddress.com';

if (substr( $str, 0, 4 ) === "http") {
    // true
}

if (strlen( $str >= 7 )) {
    // true
}

EDIT For anybody else that is interested I found this great page which runs live comparisons of various different functions. It doesn't address my particular one but very informative all the same.

Answer 1

You can run following code in any of online php editors below using different inputs and observe the speed performance.

http://www.writephponline.com/

https://www.tutorialspoint.com/php_webview_online.php

<?php
$before = microtime(true);
$str = "http";
if (substr( $str, 0, 4 ) === "http") {
    // true
}
echo "strlen performance ";
echo "Time:  " . number_format(( microtime(true) - $before), 8) . " Seconds\n";

echo "\r\n";

$before = microtime(true);
if (strlen($str >= 4)) {
    // true
}
echo "substr performance ";
echo "Time:  " . number_format(( microtime(true) - $before), 8) . " Seconds\n";
echo "\r\n";
?>

Based on multiple results from above code snippet, substr is showing better performance in terms of speed. In terms of processor load, assembly code for each function needs to compare.