/// <summary> 
        /// 轉換人民幣大小金額 
        /// </summary> 
        /// <param name="num">金額</param> 
        /// <returns>返回大寫形式</returns> 
        public static string CmycurD(decimal num)
        {
            string str1 = "零壹貳叁肆伍陸柒捌玖";            //0-9所對應的漢字 
            string
 
 str2 = "萬仟佰拾億仟佰拾萬仟佰拾元角分"; //數字位所對應的漢字 
            string str3 = "";    //從原num值中取出的值 
            string str4 = "";    //數字的字符串形式 
            string str5 = "";  //人民幣大寫金額形式 
            int i;    //循環變量 
            int j;    //num的值乘以100的字符串長度 
            string ch1 = "";    //數字的漢語讀法 
            string ch2 = ""
 
;    //數字位的漢字讀法 
            int nzero = 0;  //用來計算連續的零值是幾個 
            int temp;            //從原num值中取出的值 

            num = Math.Round(Math.Abs(num), 2);    //將num取絕對值並四舍五入取2位小數 
            str4 = ((long)(num * 100)).ToString();        //將num乘100並轉換成字符串形式 
            j = str4.Length;      //找出最高位 
            if
 
 (j > 15) { return "溢出"; }
            str2 = str2.Substring(15 - j);   //取出對應位數的str2的值。如：200.55,j為5所以str2=佰拾元角分 

            //循環取出每一位需要轉換的值 
            for (i = 0; i < j; i++)
            {
                str3 = str4.Substring(i, 1);          //取出需轉換的某一位的值 
                temp = Convert.ToInt32(str3);      //轉換為數字 
                if (i != (j - 3) && i != (j - 7) && i != (j - 11) && i != (j - 15))
                {
                    //當所取位數不為元、萬、億、萬億上的數字時 
                    if (str3 == "0")
                    {
                        ch1 = "";
                        ch2 = "";
                        nzero = nzero + 1;
                    }
                    else
                    {
                        if (str3 != "0" && nzero != 0)
                        {
                            ch1 = "零" + str1.Substring(temp * 1, 1);
                            ch2 = str2.Substring(i, 1);
                            nzero = 0;
                        }
                        else
                        {
                            ch1 = str1.Substring(temp * 1, 1);
                            ch2 = str2.Substring(i, 1);
                            nzero = 0;
                        }
                    }
                }
                else
                {
                    //該位是萬億，億，萬，元位等關鍵位 
                    if (str3 != "0" && nzero != 0)
                    {
                        ch1 = "零" + str1.Substring(temp * 1, 1);
                        ch2 = str2.Substring(i, 1);
                        nzero = 0;
                    }
                    else
                    {
                        if (str3 != "0" && nzero == 0)
                        {
                            ch1 = str1.Substring(temp * 1, 1);
                            ch2 = str2.Substring(i, 1);
                            nzero = 0;
                        }
                        else
                        {
                            if (str3 == "0" && nzero >= 3)
                            {
                                ch1 = "";
                                ch2 = "";
                                nzero = nzero + 1;
                            }
                            else
                            {
                                if (j >= 11)
                                {
                                    ch1 = "";
                                    nzero = nzero + 1;
                                }
                                else
                                {
                                    ch1 = "";
                                    ch2 = str2.Substring(i, 1);
                                    nzero = nzero + 1;
                                }
                            }
                        }
                    }
                }
                if (i == (j - 11) || i == (j - 3))
                {
                    //如果該位是億位或元位，則必須寫上 
                    ch2 = str2.Substring(i, 1);
                }
                str5 = str5 + ch1 + ch2;

                if (i == j - 1 && str3 == "0")
                {
                    //最後一位（分）為0時，加上“整” 
                    str5 = str5 + ‘整‘;
                }
            }
            if (num == 0)
            {
                str5 = "零元整";
            }
            return str5;
        }

        /**/
        /// <summary> 
        /// 一個重載，將字符串先轉換成數字在調用CmycurD(decimal num) 
        /// </summary> 
        /// <param name="num">用戶輸入的金額，字符串形式未轉成decimal</param> 
        /// <returns></returns> 
        public static string CmycurD(string numstr)
        {
            try
            {
                decimal num = Convert.ToDecimal(numstr);
                return CmycurD(num);
            }
            catch
            {
                return "非數字形式！";
            }
        }

C# 把小寫人民幣轉換為大寫