/*  
* 中文截取，支持gb2312,big5  
* 编程之家  (jb51.cc) 
* @param string $str 要截取的字串  
* @param int $start 截取起始位置  
* @param int $length 截取长度  
* @param string $charset utf-8|gb2312|gbk|big5 编码  
* @param $suffix 是否加尾缀  
*/
public function csubstr($str,$start=0,$length,$charset="utf-8",$suffix=true)  
{  
   if(function_exists("mb_substr"))  
   {  
       if(mb_strlen($str,$charset) <= $length) return $str;  
       $slice = mb_substr($str,$start,$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,$match);  
       if(count($match[0]) <= $length) return $str;  
       $slice = join("",array_slice($match[0],$length));  
   }  
   if($suffix) return $slice."…";  
   return $slice;  
}


# End 512.笔记 jb51.cc