function msubpost($str, $start=0, $length=18, $charset="utf-8", $suffix=false) {
  if(strlen($str) > ($length*2)){
    $suffix = true;
  }else{
    $suffix = false;
  }
  if(function_exists('iconv_substr') || $charset=="utf-8") {
    $slice = iconv_substr($str,$start,$length,$charset);
    if(false === $slice) {
        $slice = '';
    }
  }elseif(function_exists("mb_substr")){
    $slice = mb_substr($str, $start, $length, $charset);
  }else{
    $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));
  }
  return $suffix ? $slice.'...' : $slice;
}