Random Alphanumeric String Generator

gistfile1.php

<?php
function random_string($length, $max = false)
{
    if (is_int($max) && $max > $length) {
        $length = mt_rand($length, $max);
    }
    $output = '';

    for ($i = 0; $i < $length; $i++) {
        $which = mt_rand(0, 2);

        if ($which === 0) {
            $output .= mt_rand(0, 9);
        } elseif ($which === 1) {
            $output .= chr(mt_rand(65, 90));
        } else {
            $output .= chr(mt_rand(97, 122));
        }
    }
    return $output;
}

echo random_string(32);

?>