public static function cutstr($string, $length, $suffix = true, $charset = "utf-8", $start = 0, $dot = ' ...')
    {
        $str = str_replace(['&amp;', '&quot;', '&lt;', '&gt;'], ['&', '"', '<', '>'], $string);
        if (function_exists("mb_substr")) {
            $strcut = mb_substr($str, $start, $length, $charset);
            if (mb_strlen($str, $charset) > $length) {
                return $suffix ? $strcut . $dot : $strcut;
            }
            return $strcut;
        }
        $re = [];
        $match = [''];
        $re['utf-8'] = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
        $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
        $re['gbk'] = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
        $re['big5'] = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
        preg_match_all($re[$charset], $str, $match);
        $slice = join("", array_slice($match[0], $start, $length));
        $strcut = str_replace(['&', '"', '<', '>'], ['&amp;', '&quot;', '&lt;', '&gt;'], $slice);
        return $suffix ? $strcut . $dot : $strcut;
    }