1. 截取GB2312中文字符串< ?php   //截取中文字符串  function mysubstr($str, $start, $len) {      $tmpstr = "";      $strlen = $start + $len;      for($i = 0; $i < $strlen; $i++) {          if(ord(substr($str, $i, 1)) > 0xa0) {              $tmpstr .= substr($str, $i, 2);              $i++;          } else              $tmpstr .= substr($str, $i, 1);      }      return $tmpstr;  }  ?> 2. 截取utf8编码的多字节字符串< ?php  //截取utf8字符串  function utf8Substr($str, $from, $len)  {      return preg_replace('#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$from.'}'.                         '((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$len.'}).*#s',                         '$1',$str);  }  ?> 3. UTF-8、GB2312都支持的汉字截取函数< ?php  /*   Utf-8、gb2312都支持的汉字截取函数   cut_str(字符串, 截取长度, 开始长度, 编码);   编码默认为 utf-8   开始长度默认为 0   */      function cut_str($string, $sublen, $start = 0, $code = 'UTF-8')   {       if($code == 'UTF-8')       {           $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";           preg_match_all($pa, $string, $t_string);              if(count($t_string[0]) - $start > $sublen) return join('', array_slice($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;       }   }      $str = "abcd需要截取的字符串";   echo cut_str($str, 8, 0, 'gb2312');   ?> 4. BugFree 的字符截取函数< ?php   /**    * @package     BugFree    * @version     $Id: FunctionsMain.inc.php,v 1.32 2005/09/24 11:38:37 wwccss Exp $    *    *    * Return part of a string(Enhance the function substr())    *    *                    Chunsheng Wang 
    
         * @param string  $String  the string to cut.    * @param int     $Length  the length of returned string.    * @param booble  $Append  whether append "...": false|true    *   string           the cutted string.    */   function sysSubStr($String,$Length,$Append = false)   {       if (strlen($String) < = $Length )       {           return $String;       }       else       {           $I = 0;           while ($I < $Length)           {               $StringTMP = substr($String,$I,1);               if ( ord($StringTMP) >=224 )               {                   $StringTMP = substr($String,$I,3);                   $I = $I + 3;               }               elseif( ord($StringTMP) >=192 )               {                   $StringTMP = substr($String,$I,2);                   $I = $I + 2;               }               else               {                   $I = $I + 1;               }               $StringLast[] = $StringTMP;           }           $StringLast = implode("",$StringLast);           if($Append)           {               $StringLast .= "...";           }           return $StringLast;       }   }      $String = "CodeBit.cn -- 简单、精彩、通用";   $Length = "18";   $Append = false;   echo sysSubStr($String,$Length,$Append);   ?>