可能代码比较臃肿，希望有朋友再帮忙改正

//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";
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 " ";
}