PHP Chinese interception string function (very useful)

/**
* Chinese string interception function
* by bbs.it-home.org
*/
function cut_str($string,$sublen,$filter=true,$start=0,$code='UTF-8'){
 if($filter) $string=Html2Text($string);
 if($code=='UTF-8'){
  $pa="/[x01-x7f]|[xc2-xdf][x80-xbf]|[xe0-xef][x80-xbf]{2}|[xf0-xff][x80-xbf]{3}/";
  preg_match_all($pa,$string,$t_string);
  if(count($t_string[0])-$start>$sublen) return join('',array_slice($t_string[0],$start,$sublen))."...";
  return join('',array_slice($t_string[0],$start,$sublen));
 }else{
  $start=$start*2;
  $sublen=$sublen*2;
  $strlen=strlen($string);
  $tmpstr='';
  for($i=0;$i<$strlen;$i++){
   if($i>=$start&&$i<($start+$sublen)){
    if(ord(substr($string,$i,1))>129){
     $tmpstr.=substr($string,$i,2);
    }else{
     $tmpstr.=substr($string,$i,1);
    }
   }
   if(ord(substr($string,$i,1))>129) $i++;
  }
  if(strlen($tmpstr)<$strlen ) $tmpstr.="...";
  return $tmpstr;
 }
}
//html转换函数
function Html2Text($str){
 $str = preg_replace("/||/isU","",$str);
 $alltext = "";
 $start = 1;
 for($i=0;$i  if($start==0 && $str[$i]==">"){
   $start = 1;
  }else if($start==1){
   if($str[$i]=="<"){
    $start = 0;
    $alltext .= " ";
   }else if(ord($str[$i])>31){
    $alltext .= $str[$i];
   }
  }
 }
 $alltext = str_replace("　"," ",$alltext);
 $alltext = preg_replace("/&([^;&]*)(;|&)/","",$alltext);
 $alltext = preg_replace("/[ ]+/s"," ",$alltext);
 return $alltext;
}