msubstr
function msubstr($str, $start=0, $length, $charset=utf-8, $suffix=true){
        if(function_exists(mb_substr))
            return mb_substr($str, $start, $length, $charset);
        elseif(function_exists('iconv_substr')) {
            return iconv_substr($str,$start,$length,$charset);
        }
        $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, $length));
        if($suffix) return $slice.…;
        return $slice;
    }
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