Substract text and don't breaks words

// works with multibyte strings
// doesn't uses regexes
function substr_text($string, $length)
{
    if (mb_strlen($string, 'UTF-8') <= $length)
    {
        return $string;
    }
    else {
        return mb_substr($string, 0, strrpos(mb_substr($string, 0, $length), ' '));
    }
}