當被檢索物件資料量較大時，我們希望輸入某條記錄的拼音首字母，就可以顯示一個下拉單，顯示出符合條件的記錄。

實現：

語言： C#；

輸入框：txtSearch；

下拉框：ListBox（這個地方也沒想到更好的辦法，如果有更好的辦法，歡迎分享）

首先，把漢字字串轉為拼音首字母：

        /// <summary>
        /// 把漢字字串轉為拼音首字母
        /// </summary>
        /// <param name="ChineseStr">待轉中文字串</param>
        /// <returns></returns>
        public static string ChineseCap(string ChineseStr)
        {
            string Capstr = string.Empty;
            //每個漢字儲存需要兩個位元組
            byte[] ZW = new byte[2];
            // 漢字的整數表示形式
            long ChineseStr_int = 0;
            // 取出一個漢字
            string CharStr = string.Empty;
            // 漢字首字母
            string ChinaStr = string.Empty;

            for (int i = 0; i <= ChineseStr.Length - 1; i++)
            {
                //取出一個漢字
                CharStr = ChineseStr.Substring(i, 1).ToString();
                //得到漢字的位元組表示
                ZW = System.Text.Encoding.Default.GetBytes(CharStr);

                // 得到漢字元的位元組陣列 
                if (ZW.Length == 2)
                {
                    int i1 = (short)(ZW[0]);
                    int i2 = (short)(ZW[1]);
                    ChineseStr_int = i1 * 256 + i2;
                    #region 引數
                    //table of the constant list 
                    // 'A';      //45217..45252 
                    // 'B';      //45253..45760 
                    // 'C';      //45761..46317 
                    // 'D';      //46318..46825 
                    // 'E';      //46826..47009 
                    // 'F';      //47010..47296 
                    // 'G';      //47297..47613 

                    // 'H';      //47614..48118 
                    // 'J';      //48119..49061 
                    // 'K';      //49062..49323 
                    // 'L';      //49324..49895 
                    // 'M';      //49896..50370 
                    // 'N';      //50371..50613 
                    // 'O';      //50614..50621 
                    // 'P';      //50622..50905 
                    // 'Q';      //50906..51386 

                    // 'R';      //51387..51445 
                    // 'S';      //51446..52217 
                    // 'T';      //52218..52697 
                    //沒有U,V 
                    // 'W';      //52698..52979 
                    // 'X';      //52980..53640 
                    // 'Y';      //53689..54480 
                    // 'Z';      //54481..55289 
                    #endregion

                    #region 判斷
                    if ((ChineseStr_int >= 45217) && (ChineseStr_int <= 45252))
                    {
                        ChinaStr = "A";
                    }
                    else if ((ChineseStr_int >= 45253) && (ChineseStr_int <= 45760))
                    {
                        ChinaStr = "B";
                    }
                    else if ((ChineseStr_int >= 45761) && (ChineseStr_int <= 46317))
                    {
                        ChinaStr = "C";
                    }
                    else if ((ChineseStr_int >= 46318) && (ChineseStr_int <= 46825))
                    {
                        ChinaStr = "D";
                    }
                    else if ((ChineseStr_int >= 46826) && (ChineseStr_int <= 47009))
                    {
                        ChinaStr = "E";
                    }
                    else if ((ChineseStr_int >= 47010) && (ChineseStr_int <= 47296))
                    {
                        ChinaStr = "F";
                    }
                    else if ((ChineseStr_int >= 47297) && (ChineseStr_int <= 47613))
                    {
                        ChinaStr = "G";
                    }
                    else if ((ChineseStr_int >= 47614) && (ChineseStr_int <= 48118))
                    {
                        ChinaStr = "H";
                    }
                    else if ((ChineseStr_int >= 48119) && (ChineseStr_int <= 49061))
                    {
                        ChinaStr = "J";
                    }
                    else if ((ChineseStr_int >= 49062) && (ChineseStr_int <= 49323))
                    {
                        ChinaStr = "K";
                    }
                    else if ((ChineseStr_int >= 49324) && (ChineseStr_int <= 49895))
                    {
                        ChinaStr = "L";
                    }
                    else if ((ChineseStr_int >= 49896) && (ChineseStr_int <= 50370))
                    {
                        ChinaStr = "M";
                    }
                    else if ((ChineseStr_int >= 50371) && (ChineseStr_int <= 50613))
                    {
                        ChinaStr = "N";
                    }
                    else if ((ChineseStr_int >= 50614) && (ChineseStr_int <= 50621))
                    {
                        ChinaStr = "O";
                    }
                    else if ((ChineseStr_int >= 50622) && (ChineseStr_int <= 50905))
                    {
                        ChinaStr = "P";
                    }
                    else if ((ChineseStr_int >= 50906) && (ChineseStr_int <= 51386))
                    {
                        ChinaStr = "Q";
                    }
                    else if ((ChineseStr_int >= 51387) && (ChineseStr_int <= 51445))
                    {
                        ChinaStr = "R";
                    }
                    else if ((ChineseStr_int >= 51446) && (ChineseStr_int <= 52217))
                    {
                        ChinaStr = "S";
                    }
                    else if ((ChineseStr_int >= 52218) && (ChineseStr_int <= 52697))
                    {
                        ChinaStr = "T";
                    }
                    else if ((ChineseStr_int >= 52698) && (ChineseStr_int <= 52979))
                    {
                        ChinaStr = "W";
                    }
                    else if ((ChineseStr_int >= 52980) && (ChineseStr_int <= 53640))
                    {
                        ChinaStr = "X";
                    }
                    else if ((ChineseStr_int >= 53689) && (ChineseStr_int <= 54480))
                    {
                        ChinaStr = "Y";
                    }
                    else if ((ChineseStr_int >= 54481) && (ChineseStr_int <= 55289))
                    {
                        ChinaStr = "Z";
                    }
                    #endregion
                }
                else
                {
                    // 非漢字時退出
                    //Capstr = ChineseStr;
                    break;
                }
                Capstr = Capstr + ChinaStr;
            }
            return Capstr;
        }
 

txtSearch輸入拼音首字母，顯示下拉單：

        /// <summary>
        /// 接收輸入字元
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void txtSearch_KeyUp(object sender, KeyEventArgs e)
        {
            char tmp = (char)e.KeyValue;
            try
            {
                // 臨時儲存
                Dictionary<string, string> tmpDic = new Dictionary<string, string>();

                if (null == tmpFutureType)
                { tmpFutureType = new Dictionary<string, string>(); }

                int id = txtSearch.Text.Trim().Length;
                if (id < 1)
                { tmpFutureType.Clear(); return; }

                if (tmpFutureType.Count > 0)
                {
                    foreach (string key in tmpFutureType.Keys)
                    {
                        if (key.Length >= id)
                        {
                            if (tmp.ToString().Equals(key.Substring(id - 1, 1)))
                            {
                                // 加入臨時佇列
                                tmpDic.Add(key, tmpFutureType[key]);
                            }
                        }
                    }
                    tmpFutureType.Clear();
                    // 從臨時佇列中複製到tmpFutureType
                    tmpFutureType = tmpDic;
                }
                else
                {
                    foreach (string key in CGlobal.DicFutureTypePinYin.Keys)
                    {
                        if (key.Length >= id)
                        {
                            if (tmp.ToString().Equals(key.Substring(id - 1, 1)))
                            {
                                // 加入tmpFutureType
                                tmpFutureType.Add(key, CGlobal.DicFutureTypePinYin[key]);
                            }
                        }
                    }
                }

                // 加入下拉列表
                lboxTmp.Items.Clear();
                foreach (string key in tmpFutureType.Keys)
                {
                    lboxTmp.Items.Add(tmpFutureType[key]);
                }
                if (lboxTmp.Items.Count > 0)
                {
                    lboxTmp.Visible = true;
                }
            }
            catch (Exception ex)
            {
                CGlobal._logHelper.WriteLog(LogStyle.eError, ex.Message);
            }
        }