C#转换人民币大写金额

/// <summary>
  /// 转换人民币大写金额。
  /// </summary>
  public class RMBConverter
  {
      /// <summary>
      /// 转换人民币大小金额
      /// </summary>
      /// <param name="num">金额</param>
      /// <returns>返回大写形式</returns>
      public static string toRMB(decimal num)
      {
          string str1 = "零壹贰叁肆伍陆柒捌玖"; //0-9所对应的汉字
          string str2 = "万仟佰拾亿仟佰拾万仟佰拾元角分"; //数字位所对应的汉字
          string str3 = ""; //从原num值中取出的值
          string str4 = ""; //数字的字符串形式
          string str5 = ""; //人民币大写金额形式
          int i; //循环变量
          int j; //num的值乘以100的字符串长度
          string ch1 = ""; //数字的汉语读法
          string ch2 = ""; //数字位的汉字读法
          int nzero = 0; //用来计算连续的零值是几个
          int temp; //从原num值中取出的值
          num = Math.Round(Math.Abs(num), 2); //将num取绝对值并四舍五入取2位小数
          str4 = ((long)(num * 100)).ToString(); //将num乘100并转换成字符串形式
          j = str4.Length; //找出最高位
          if (j > 15) { return "溢出"; }
          str2 = str2.Substring(15 - j); //取出对应位数的str2的值。如：200.55,j为5所以str2=佰拾元角分
          //循环取出每一位需要转换的值
          for (i = 0; i < j; i++)
          {
              str3 = str4.Substring(i, 1); //取出需转换的某一位的值
              temp = Convert.ToInt32(str3); //转换为数字
              if (i != (j - 3) && i != (j - 7) && i != (j - 11) && i != (j - 15))
              {
                  //当所取位数不为元、万、亿、万亿上的数字时
                  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
              {
                  //该位是万亿，亿，万，元位等关键位
                  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))
              {
                  //如果该位是亿位或元位，则必须写上
                  ch2 = str2.Substring(i, 1);
              }
              str5 = str5 + ch1 + ch2;
              if (i == j - 1 && str3 == "0")
              {
                  //最后一位（分）为0时，加上“整”
                  str5 = str5 + '整';
              }
          }
          if (num == 0)
          {
              str5 = "零元整";
          }
          return str5;
      }

  }