php截取中文字符串 GB2312 utf-8

UTF-8截取中文字符串
   function Cn_Substr($string, $length) {
        preg_match_all("/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]|xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/", $string, $info);  
        for($i=0; $i<count($info[0]); $i++) {
 $wordscut .= $info[0][$i];
 $j = ord($info[0][$i]) > 127 ? $j + 2 : $j + 1;
 if ($j > $length - 3) {
 return $wordscut." ...";
 }
        }
        return join('', $info[0]);
   }
GB2312截取中文字符串
   function Cn_Substrs($strs,$lens){
      if (strlen($strs)<$lens) {
          $nstrs=$strs;
      }else{
          $mlens=$lens;
          for ($i=0;$i<=strlen($strs) && $mlens>0;$i++){
             $chars=substr($strs,$i,1);
             if(ord($chars)>0xa0 ) { 
                $i++;
                $mlens -=2;;
             }else{
                $mlens--;
             }
          }
          $nstrs=substr($strs,0,$i)."...";
      }
      return $nstrs;
   }