asp.net获取中文汉字的首字母

 /// <summary>
  /// 通过汉字区位码得到其首字母(小写)
  /// </summary>
  /// <param name="nCode">汉字编码</param>
  /// <returns></returns>
  public string FirstLetter(int nCode) {
   if (nCode >= 1601 && nCode < 1637) return "a";
   if (nCode >= 1637 && nCode < 1833) return "b";
   if (nCode >= 1833 && nCode < 2078) return "c";
   if (nCode >= 2078 && nCode < 2274) return "d";
   if (nCode >= 2274 && nCode < 2302) return "e";
   if (nCode >= 2302 && nCode < 2433) return "f";
   if (nCode >= 2433 && nCode < 2594) return "g";
   if (nCode >= 2594 && nCode < 2787) return "h";
   if (nCode >= 2787 && nCode < 3106) return "j";
   if (nCode >= 3106 && nCode < 3212) return "k";
   if (nCode >= 3212 && nCode < 3472) return "l";
   if (nCode >= 3472 && nCode < 3635) return "m";
   if (nCode >= 3635 && nCode < 3722) return "n";
   if (nCode >= 3722 && nCode < 3730) return "o";
   if (nCode >= 3730 && nCode < 3858) return "p";
   if (nCode >= 3858 && nCode < 4027) return "q";
   if (nCode >= 4027 && nCode < 4086) return "r";
   if (nCode >= 4086 && nCode < 4390) return "s";
   if (nCode >= 4390 && nCode < 4558) return "t";
   if (nCode >= 4558 && nCode < 4684) return "w";
   if (nCode >= 4684 && nCode < 4925) return "x";
   if (nCode >= 4925 && nCode < 5249) return "y";
   if (nCode >= 5249 && nCode < 5590) return "z";
   return "";
  }

 ///   <summary> 
  ///   判断是否为汉字 
  ///   </summary> 
  ///   <param   name="chrStr">待检测字符串</param> 
  ///   <returns>是汉字返回true</returns> 
  public bool IsChineseCharacters(string chrStr) {
   Regex CheckStr = new Regex("[u4e00-u9fa5]");
   return CheckStr.IsMatch(chrStr);
  }

  /// <summary>
  /// 得到每个汉字的字首拼音码字母(小写)
  /// </summary>
  /// <param name="chrStr">输入字符串</param>
  /// <returns>返回结果</returns>
  private string ChangeByName(string chrStr) {
   string strHeadString = string.Empty;
   Encoding gb = System.Text.Encoding.GetEncoding("gb2312");
   for (int i = 0; i < chrStr.Length; i++) {
    //检测该字符是否为汉字
    if (!IsChineseCharacters(chrStr.Substring(i, 1))) {
     strHeadString += chrStr.Substring(i, 1);
     continue;
    }
    byte[] bytes = gb.GetBytes(chrStr.Substring(i, 1));
    string lowCode = System.Convert.ToString(bytes[0] - 0xA0, 16);
    string hightCode = System.Convert.ToString(bytes[1] - 0xA0, 16);
    int nCode = Convert.ToUInt16(lowCode, 16) * 100 + Convert.ToUInt16(hightCode, 16);      //得到区位码
    strHeadString += FirstLetter(nCode);
   }
   return strHeadString;
  }