.net c# 取中文汉字的首字母

程序中经常需要用到汉字的首字母来进行检索文字,首先需要转换成首字母

方法一:

        /// <summary>
        /// 取字符串首字母(包括中文)
        /// </summary>
        /// <param name="name">字符串</param>
        /// <returns>首字母</returns>
        public static string FirstLetter(string name)
        {
            if (string.IsNullOrEmpty(name)) return "";
            var s = name.Substring(0, 1);
            if ((int)Convert.ToChar(s) > 0 && (int)Convert.ToChar(s) < 256) return "";
            byte[] array = System.Text.Encoding.Default.GetBytes(s);
            if (array == null || array.Length < 2) return "*";
            int i = (short)(array[0] - '\0') * 256 + ((short)(array[1] - '\0'));

            if (i < 0xB0A1) return "*";
            if (i < 0xB0C5) return "A";
            if (i < 0xB2C1) return "B";
            if (i < 0xB4EE) return "C";
            if (i < 0xB6EA) return "D";
            if (i < 0xB7A2) return "E";
            if (i < 0xB8C1) return "F";
            if (i < 0xB9FE) return "G";
            if (i < 0xBBF7) return "H";
            if (i < 0xBFA6) return "J";
            if (i < 0xC0AC) return "K";
            if (i < 0xC2E8) return "L";
            if (i < 0xC4C3) return "M";
            if (i < 0xC5B6) return "N";
            if (i < 0xC5BE) return "O";
            if (i < 0xC6DA) return "P";
            if (i < 0xC8BB) return "Q";
            if (i < 0xC8F6) return "R";
            if (i < 0xCBFA) return "S";
            if (i < 0xCDDA) return "T";
            if (i < 0xCEF4) return "W";
            if (i < 0xD1B9) return "X";
            if (i < 0xD4D1) return "Y";
            if (i < 0xD7FA) return "Z";
            return "*";
        }

方法二:

	/// <summary>
        /// 得到单个字符的首字母方法2
        /// </summary>
        /// <param name="name">字符串</param>
        /// <returns></returns>
        public static string FirstLetterTwo(string name)
        {
            if (string.IsNullOrEmpty(name)) return "";
            name = name.Substring(0, 1);
            if (Convert.ToChar(name) >= 0 && Convert.ToChar(name) < 256) { return name; }
            else
            {
                Encoding gb2312 = Encoding.GetEncoding("gb2312");
                byte[] unicodeBytes = Encoding.Unicode.GetBytes(name);
                byte[] gb2312Bytes = Encoding.Convert(Encoding.Unicode, gb2312, unicodeBytes);
                return FirstLetterX(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 static string FirstLetterX(int name)
        {
            if (name >= 1601 && name < 1637) return "A";
            if (name >= 1637 && name < 1833) return "B";
            if (name >= 1833 && name < 2078) return "C";
            if (name >= 2078 && name < 2274) return "D";
            if (name >= 2274 && name < 2302) return "E";
            if (name >= 2302 && name < 2433) return "F";
            if (name >= 2433 && name < 2594) return "G";
            if (name >= 2594 && name < 2787) return "H";
            if (name >= 2787 && name < 3106) return "J";
            if (name >= 3106 && name < 3212) return "K";
            if (name >= 3212 && name < 3472) return "L";
            if (name >= 3472 && name < 3635) return "M";
            if (name >= 3635 && name < 3722) return "N";
            if (name >= 3722 && name < 3730) return "O";
            if (name >= 3730 && name < 3858) return "P";
            if (name >= 3858 && name < 4027) return "Q";
            if (name >= 4027 && name < 4086) return "R";
            if (name >= 4086 && name < 4390) return "S";
            if (name >= 4390 && name < 4558) return "T";
            if (name >= 4558 && name < 4684) return "W";
            if (name >= 4684 && name < 4925) return "X";
            if (name >= 4925 && name < 5249) return "Y";
            if (name >= 5249 && name <= 5589) return "Z";
            if (name >= 5601 && name <= 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 = name.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 "0";
        }

方法三:

        /// <summary>
        /// 得到单个字符的首字母方法3
        /// </summary>
        /// <param name="cnChar"></param>
        /// <returns></returns>
        public static string FirstLetterThere(string cnChar)
        {
            byte[] arrCN = Encoding.Default.GetBytes(cnChar);
            if (arrCN.Length > 1)
            {
                int area = (short)arrCN[0];

                int pos = (short)arrCN[1];
                int code = (area << 8) + pos;
                int[] areacode = { 45217, 45253, 45761, 46318, 46826, 47010, 47297, 47614, 48119, 48119, 49062, 49324, 49896, 50371, 50614, 50622, 50906, 51387, 51446, 52218, 52698, 52698, 52698, 52980, 53689, 54481 };
                for (int i = 0; i < 26; i++)
                {
                    int max = 55290;
                    if (i != 25) max = areacode[i + 1];
                    if (areacode[i] <= code && code < max)
                    {
                        return Encoding.Default.GetString(new byte[] { (byte)(65 + i) });
                    }
                }
                return "*";
            }
            else return cnChar;
        }