Also send a function to generate random strings

/**
 * Generate random numbers
 *
 * @param int $length Generate string length
 * @param int $type String type
 * @param bool $special Whether to use special characters
 * @return string Return the generated random string
 * @example random(10, null, true);
*/
function random($length, $type = NULL, $special = FALSE) {
	$str = "";
	switch ($type) {
		case 1:
			$str = "0123456789";
			break;
		case 2:
			$str = "abcdefghijklmnopqrstuvwxyz";
			break;
		case 3:
			$str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
			break;
		case 4:
			$str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
			break;
		default:
			$str = "abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789";
		break;
	}
	return substr(str_shuffle(($special != FALSE) ? '!@#$%^&*()_+' . $str : $str), 0, $length);
}