asp.net 汉字取首字母

//返回给定字符串的首字母

private String IndexCode(String IndexTxt)
          {
              String _Temp = null;
              for (int i = 0; i < IndexTxt.Length; i++)
                  _Temp = _Temp + GetOneIndex(IndexTxt.Substring(i, 1));
              return _Temp;
          }

          //得到单个字符的首字母
          private String GetOneIndex(String OneIndexTxt)
          {
              if (Convert.ToChar(OneIndexTxt) >= 0 && Convert.ToChar(OneIndexTxt) < 256)
                  return OneIndexTxt;
              else
              {
                  Encoding gb2312 = Encoding.GetEncoding("gb2312");
                  byte[] unicodeBytes = Encoding.Unicode.GetBytes(OneIndexTxt);
                  byte[] gb2312Bytes = Encoding.Convert(Encoding.Unicode, gb2312, unicodeBytes);
                  return GetX(Convert.ToInt32(
                  String.Format("{0:D2}", Convert.ToInt16(gb2312Bytes[0]) - 160)
                  + String.Format("{0:D2}", Convert.ToInt16(gb2312Bytes[1]) - 160)
                  ));
              }

          }

          //根据区位得到首字母
          private String GetX(int GBCode)
          {
              if (GBCode >= 1601 && GBCode < 1637) return "A";
              if (GBCode >= 1637 && GBCode < 1833) return "B";
              if (GBCode >= 1833 && GBCode < 2078) return "C";
              if (GBCode >= 2078 && GBCode < 2274) return "D";
              if (GBCode >= 2274 && GBCode < 2302) return "E";
              if (GBCode >= 2302 && GBCode < 2433) return "F";
              if (GBCode >= 2433 && GBCode < 2594) return "G";
              if (GBCode >= 2594 && GBCode < 2787) return "H";
              if (GBCode >= 2787 && GBCode < 3106) return "J";
              if (GBCode >= 3106 && GBCode < 3212) return "K";
              if (GBCode >= 3212 && GBCode < 3472) return "L";
              if (GBCode >= 3472 && GBCode < 3635) return "M";
              if (GBCode >= 3635 && GBCode < 3722) return "N";
              if (GBCode >= 3722 && GBCode < 3730) return "O";
              if (GBCode >= 3730 && GBCode < 3858) return "P";
              if (GBCode >= 3858 && GBCode < 4027) return "Q";
              if (GBCode >= 4027 && GBCode < 4086) return "R";
              if (GBCode >= 4086 && GBCode < 4390) return "S";
            
4000
  if (GBCode >= 4390 && GBCode < 4558) return "T";
              if (GBCode >= 4558 && GBCode < 4684) return "W";
              if (GBCode >= 4684 && GBCode < 4925) return "X";
              if (GBCode >= 4925 && GBCode < 5249) return "Y";
              if (GBCode >= 5249 && GBCode <= 5589) return "Z";
              if (GBCode >= 5601 && GBCode <= 8794)
              {
                  String CodeData = "cjwgnspgcenegypbtwxzdxykygtpjnmjqmbsgzscyjsyyfpggbzgydywjkgaljswkbjqhyjwpdzlsgmr"
                  + "ybywwccgznkydgttngjeyekzydcjnmcylqlypyqbqrpzslwbdgkjfyxjwcltbncxjjjjcxdtqsqzycdxxhgckbphffss"
                  + "pybgmxjbbyglbhlssmzmpjhsojnghdzcdklgjhsgqzhxqgkezzwymcscjnyetxadzpmdssmzjjqjyzcjjfwqjbdzbjgd"
                  + "nzcbwhgxhqkmwfbpbqdtjjzkqhylcgxfptyjyyzpsjlfchmqshgmmxsxjpkdcmbbqbefsjwhwwgckpylqbgldlcctnma"
                  + "eddksjngkcsgxlhzaybdbtsdkdylhgymylcxpycjndqjwxqxfyyfjlejbzrwccqhqcsbzkymgplbmcrqcflnymyqmsqt"
                  + "rbcjthztqfrxchxmcjcjlxqgjmshzkbswxemdlckfsydsglycjjssjnqbjctyhbftdcyjdgwyghqfrxwckqkxebpdjpx"
                  + "jqsrmebwgjlbjslyysmdxlclqkxlhtjrjjmbjhxhwywcbhtrxxglhjhfbmgykldyxzpplggpmtcbbajjzyljtyanjgbj"
                  + "flqgdzyqcaxbkclecjsznslyzhlxlzcghbxzhznytdsbcjkdlzayffydlabbgqszkggldndnyskjshdlxxbcghxyggdj"
                  + "mmzngmmccgwzszxsjbznmlzdthcqydbdllscddnlkjyhjsycjlkohqasdhnhcsgaehdaashtcplcpqybsdmpjlpcjaql"
                  + "cdhjjasprchngjnlhlyyqyhwzpnccgwwmzffjqqqqxxaclbhkdjxdgmmydjxzllsygxgkjrywzwyclzmcsjzldbndcfc"
                  + "xyhlschycjqppqagmnyxpfrkssbjlyxyjjglnscmhcwwmnzjjlhmhchsyppttxrycsxbyhcsmxjsxnbwgpxxtaybgajc"
                  + "xlypdccwqocwkccsbnhcpdyznbcyytyckskybsqkkytqqxfcwchcwkelcqbsqyjqcclmthsywhmktlkjlychwheqjhtj"
                  + "hppqpqscfymmcmgbmhglgsllysdllljpchmjhwljcyhzjxhdxjlhxrswlwzjcbxmhzqxsdzpmgfcsglsdymjshxpjxom"
                  + "yqknmyblrthbcftpmgyxlchlhlzylxgsssscclsldclepbhshxyyfhbmgdfycnjqwlqhjjcywjztejjdhfblqxtqkwhd"
                  + "chqxagtlxljxmsljhdzkzjecxjcjnmbbjcsfywkbjzghysdcpqyrsljpclpwxsdwejbjcbcnaytmgmbapclyqbclzxcb"
                  + "nmsggfnzjjbzsfqyndxhpcqkzczwalsbccjxpozgwkybsgxfcfcdkhjbstlqfsgdslqwzkxtmhsbgzhjcrglyjbpmljs"
                  + "xlcjqqhzmjczydjwbmjklddpmjegxyhylxhlqyqhkycwcjmyhxnatjhyccxzpcqlbzwwwtwbqcmlbmynjcccxbbsnzzl"
                  + "jpljxyztzlgcldcklyrzzgqtgjhhgjljaxfgfjzslcfdqzlclgjdjcsnclljpjqdcclcjxmyzftsxgcgsbrzxjqqcczh"
                  + "gyjdjqqlzxjyldlbcyamcstylbdjbyregklzdzhldszchznwczcllwjqjjjkdgjcolbbzppglghtgzcygezmycnqcycy"
                  + "hbhgxkamtxyxnbskyzzgjzlqjdfcjxdygjqjjpmgwgjjjpkjsbgbmmcjssclpqpdxcdyykypcjddyygywchjrtgcnyql"
                  + "dkljczzgzccjgdyksgpzmdlcphnjafyzdjcnmwescsglbtzcgmsdllyxqsxsbljsbbsgghfjlwpmzjnlyywdqshzxtyy"
                  + "whmcyhywdbxbtlmswyyfsbjcbdxxlhjhfpsxzqhfzmqcztqcxzxrdkdjhnnyzqqfnqdmmgnydxmjgdhcdycbffallztd"
                  + "ltfkmxqzdngeqdbdczjdxbzgsqqddjcmbkxffxmkdmcsychzcmljdjynhprsjmkmpcklgdbqtfzswtfgglyplljzhgjj"
                  + "gypzltcsmcnbtjbhfkdhbyzgkpbbymtdlsxsbnpdkleycjnycdykzddhqgsdzsctarlltkzlgecllkjljjaqnbdggghf"
                  + "jtzqjsecshalqfmmgjnlyjbbtmlycxdcjpldlpcqdhsycbzsckbzmsljflhrbjsnbrgjhxpdgdjybzgdlgcsezgxlblg"
                  + "yxtwmabchecmwyjyzlljjshlgndjlslygkdzpzxjyyzlpcxszfgwyydlyhcljscmbjhblyjlycblydpdqysxktbytdkd"
                  + "xjypcnrjmfdjgklccjbctbjddbblblcdqrppxjcglzcshltoljnmdddlngkaqakgjgyhheznmshrphqqjchgmfprxcjg"
                  + "dychghlyrzqlcngjnzsqdkqjymszswlcfqjqxgbggxmdjwlmcrnfkkfsyyljbmqammmycctbshcptxxzzsmphfshmclm"
                  + "ldjfyqxsdyjdjjzzhqpdszglssjbckbxyqzjsgpsxjzqznqtbdkwxjkhhgflbcsmdldgdzdblzkycqnncsybzbfglzzx"
                  + "swmsccmqnjqsbdqsjtxxmbldxcclzshzcxrqjgjylxzfjphymzqqydfqjjlcznzjcdgzygcdxmzysctlkphtxhtlbjxj"
                  + "lxscdqccbbqjfqzfsltjbtkqbsxjjljchczdbzjdczjccprnlqcgpfczlclcxzdmxmphgsgzgszzqjxlwtjpfsyaslcj"
                  + "btckwcwmytcsjjljcqlwzmalbxyfbpnlschtgjwejjxxglljstgshjqlzfkcgnndszfdeqfhbsaqdgylbxmmygszldyd"
                  + "jmjjrgbjgkgdhgkblgkbdmbylxwcxyttybkmrjjzxqjbhlmhmjjzmqasldcyxyqdlqcafywyxqhz";
                  String _gbcode = GBCode.ToString();
                  int pos = (Convert.ToInt16(_gbcode.Substring(0, 2)) - 56) * 94 + Convert.ToInt16(_gbcode.Substring(_gbcode.Length - 2, 2));
                  return CodeData.Substring(pos - 1, 1);
              }
              return " ";
          }