C#中英文混合字符串过长截断

 /// <summary>
         /// 截断字符串
         /// </summary>
         /// <param name="maxLength">最大长度</param>
         /// <param name="str">原字符串</param>
         /// <returns></returns>
         public static string CutStr(int maxLength, string str)
         {
             string temp = str;
             if (Regex.Replace(temp, "[\u4e00-\u9fa5]", "zz", RegexOptions.IgnoreCase).Length <= maxLength)
             {
                 return temp;
             }
             for (int i = temp.Length; i >= ; i--)
             {
                 temp = temp.Substring(, i);
                 if (Regex.Replace(temp, "[\u4e00-\u9fa5]", "zz", RegexOptions.IgnoreCase).Length <= maxLength - )
                 {
                     return temp + "...";
                 }
             }
             return "...";
         }