大写金额字符串生成 C#实现

思路：
　　中文对金额的描述以四位为一组，
　　只考虑一万亿以内的数字则每组内以千、百、十和[亿\万\元]区分各位
　　连续的零按一个处理，组内最低位的零可略去
　　无角无分说整，有角无分只说角，无角有分说零X分，有角有分...

代码：

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;

 namespace MorrisSpace
 {
     /// <summary>
     /// 中文金额字符串辅助类。Helper for Amount string in Chinese
     /// </summary>
     public class AmountStringHelper
     {
         static private readonly char[] units = { '分', '角', '拾', '佰', '仟', '圆', '万', '亿', '整' };
         //                                        0     1     2     3     4     5     6     7    8
         static private readonly char[] numbers = { '零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖' };

         /// <summary>
         /// 数字金额转大写金额
         /// </summary>
         /// <param name="num">金额数字</param>
         /// <returns>大写金额字符串</returns>
         public static string GetAmountInWords(double num)
         {
             double amount = Math.Round(num, );
             long integ = (int)amount;
             double fract = Math.Round(amount - integ, );
             if (integ.ToString().Length > )
             {
                 return null;
             }
             string result = "";
             if (fract - 0.0 != )
             {
                 string tempstr = fract.ToString();
                 if (tempstr.Length == )
                 {
                     result += numbers[(int)(fract * )];
                     result += units[];
                 }
                 else
                 {
                     int frist = (int)(fract * );
                     int second = (int)(fract *  - frist * );
                     if (frist != )
                     {
                         result += numbers[frist];
                         result += units[];
                         result += numbers[second];
                         result += units[];
                     }
                     else
                     {
                         result += numbers[];
                         result += numbers[second];
                         result += units[];
                     }
                 }
             }
             else
             {
                 result += units[];
             }

             for (int temp = (int)(integ % ), secnum = ; temp != ; temp = (int)(integ % ), secnum++)
             {
                 result = FourBitTrans(temp) + units[secnum + ] + result;
                 integ /= ;
                 if (integ !=  && temp < )
                 {
                     result = numbers[] + result;
                 }
             }
             return result;
         }

         /// <summary>
         /// 进行四位数字转换的辅助函数
         /// </summary>
         /// <param name="num">四位以下数字</param>
         /// <returns>大写金额四位节</returns>
         public static string FourBitTrans(int num)
         {
             string tempstr = num.ToString();
             if (tempstr.Length > )
             {
                 return null;
             }
             string result = string.Empty;
             int i = tempstr.Length;
             int j = ;
             bool zeromark = true;
             while (--i >= )
             {
                 j++;

                 if (tempstr[i] == '')
                 {
                     if (zeromark == true)
                     {
                         continue;
                     }
                     zeromark = true;
                     result = numbers[] + result;
                     continue;
                 }
                 zeromark = false;
                 if (j > )
                 {
                     result = units[j] + result;
                 }
                 int temp = tempstr[i] - '';
                 result = numbers[temp] + result;
             }
             return result;
         }

     }
 }

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这个代码只适合一亿以内的金额，但相信以满足绝大多数情况