random_str.php

<?php

if (!function_exists('random_str')) {
    /**
     * Generate specific length random string
     *
     * @param $len
     * @param $special
     * @return string
     */
    function random_str($len = 4, $special = false)
    {
        $tuple = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        if ($special) {
            $tuple .= '!@#$%^&*()';
        }
        $str = '';
        $tupleLen = mb_strlen($tuple) - 1;
        for ($i = 0; $i < $len; $i++) {
            $str .= $tuple[mt_rand(0, $tupleLen)];
        }
        return $str;
    }
}