截取字符串,汉字占两个字节，字母占一个字节

/*

 * 页面编码必须为utf-8

 */

function esub($str, $length = 0, $ext = "...") {

     if ($length < 1) {

          return $str;

     }

     //计算字符串长度

     $strlen = (strlen($str) + mb_strlen($str, "UTF-8")) / 2;

     if ($strlen < $length) {

          return $str;

     }

     if (mb_check_encoding($str, "UTF-8")) {

          $str = mb_strcut(mb_convert_encoding($str, "GBK", "UTF-8"), 0, $length, "GBK");

          $str = mb_convert_encoding($str, "UTF-8", "GBK");

     } else {

          return "不支持的文档编码";

     }

     $str = rtrim($str, " ,.。，-——（【、；‘“??《<@");

     return $str . $ext;

}

$str = "L对每个人都说还好";