public static function lengthSort($val_1, $val_2)
    {
        // initialize the return value to zero
        $retVal = 0;

        // compare lengths
        $firstVal = strlen($val_1);
        $secondVal = strlen($val_2);

        if ($firstVal > $secondVal) {
            $retVal = 1;
        } elseif ($firstVal < $secondVal) {
            $retVal = -1;
        }

        return $retVal;
    }