php截取中文字符串函数的技巧

<?php
//中文字符串截取
function substr_zh($string,$sublen,$start=0,$code=&#39;UTF-8&#39;){
 if($code==&#39;UTF-8&#39;){
  $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";
  preg_match_all($pa,$string,$t_string);
  if(count($t_string[0])-$start > $sublen){
   return join(&#39;&#39;,array_slice($t_string[0],$start,$sublen))."...";
   //array_slice()在数组中根据条件取出一段值，参数(数组,开始位置,[长度])
  }else{
   return join(&#39;&#39;,array_slice($t_string[0],$start,$sublen));
  }
 }else{
  $start = $start*2;
  $sublen = $sublen*2;
  $strlen = strlen($string);
  $tmpstr = &#39;&#39;;
  for($i=0;$i<$strlen;$i++){
   if($i>$start && $i<($start+$sublen)){
    if(ord(substr($string,$i,1))>129){
    //ord():返回字符串第一个字符的ASCII值
    //substr():返回字符串的一部分
     $tmpstr .= substr($string,$i,2);
    }else{
     $tmpstr .= substr($string,$i,1);
    }
   }
   if(ord(substr($string,$i,1))>129){
    $i++;
   }
   if(strlen($tmpstr)<$strlen){
    $tmpstr .= "...";
   }
  }
  return $tmpstr;
 }
}
$string ="顶置车顶起困境檲上盯协押畏奇才趄肯困楞右脚可爱有";
echo substr_zh($string,10,0,&#39;gb2312&#39;);
?>