Check if string startsWith

benchmark.php

<?php
function rand_str($length, $switch_chars)
{
    $valid_chars = 'ABCDEFGHIJKLMNOPQRSabcdefghijklmnopqrs0123456789';
    if ($switch_chars) {
        $valid_chars = 'TUVWXYZtuvwxyz';
    }
    $random_string = "";

    $num_valid_chars = strlen($valid_chars);

    for ($i = 0; $i < $length; $i++)
    {
        $random_pick = mt_rand(1, $num_valid_chars);
        $random_char = $valid_chars[$random_pick-1];
        $random_string .= $random_char;
    }

    return $random_string;
}

function strncmp_strlen($haystack, $needle)
{
    return !strncmp($haystack, $needle, strlen($needle));
}

function substr_strlen($haystack, $needle)
{
    return substr($haystack, 0, strlen($needle)) === $needle;
}

function strpos_zero($haystack, $needle)
{
    return strpos($haystack, $needle) === 0;
}

function benchmark($func, $haylen, $needlen)
{
    $haystack = rand_str($haylen, false);
    $match = substr($haystack, 0, $needlen);
    $end_match = substr($haystack, strlen($haystack) - $needlen);
    $no_match = rand_str($needlen, true);

    $start = microtime(true);
    for ($i = 0; $i < 500000; $i++) {
        $func($haystack, $haystack);
        $func($haystack, $match);
        $func($haystack, $end_match);
        $func($haystack, $no_match);
    }
    $end = microtime(true);
    $time = $end - $start;

    echo $func . " time: " . sprintf('%.4f', $time) . PHP_EOL;
}


echo "Starting test with 20 letter haystack and 10 letter needle\n";

benchmark('strncmp_strlen', 20, 10);
benchmark('substr_strlen', 20, 10);
benchmark('strpos_zero', 20, 10);

echo "Starting test with 1000 letter haystack and 10 letter needle\n";

benchmark('strncmp_strlen', 1000, 10);
benchmark('substr_strlen', 1000, 10);
benchmark('strpos_zero', 1000, 10);

echo "Starting test with 1000 letter haystack and 800 letter needle\n";

benchmark('strncmp_strlen', 1000, 800);
benchmark('substr_strlen', 1000, 800);
benchmark('strpos_zero', 1000, 800);