数字转换成大写金额

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

/// <summary>
///ConvertSum 的摘要说明
/// </summary>
public class ConvertSum
{
 public ConvertSum()
 {
  //
  //TODO: 在此处添加构造函数逻辑
  //
 }
    public string ConvertSums(string str)
    {
        if (!IsPositveDecimal(str))
            return "输入的不是正数字！";
        if (Double.Parse(str) > 999999999999.99)
            return "数字太大，无法换算，请输入一万亿元以下的金额";
        char[] ch = new char[1];
        ch[0] = '.'; //小数点  
        string[] splitstr = null; //定义按小数点分割后的字符串数组  
        splitstr = str.Split(ch[0]);//按小数点分割字符串  
        if (splitstr.Length == 1) //只有整数部分  
            return ConvertData(str) + "圆整";
        else //有小数部分  
        {
            string rstr;
            rstr = ConvertData(splitstr[0]) + "圆";//转换整数部分  
            rstr += ConvertXiaoShu(splitstr[1]);//转换小数部分  
            return rstr;
        }
    }
    /// 判断是否是正数字字符串  
    /// 判断字符串  
    /// 如果是数字，返回true，否则返回false  
    public bool IsPositveDecimal(string str)
    {
        Decimal d;
        try
        {
            d = Decimal.Parse(str);
        }
        catch (Exception)
        {
            return false;
        }
        if (d > 0)
            return true;
        else
            return false;
    }
    /// 转换数字（整数）  
    /// 需要转换的整数数字字符串  
    /// 转换成中文大写后的字符串  
    public string ConvertData(string str)
    {
        string tmpstr = "";
        string rstr = "";
        int strlen = str.Length;
        if (strlen <= 4)//数字长度小于四位  
        {
            rstr = ConvertDigit(str);
        }
        else
        {
            if (strlen <= 8)//数字长度大于四位，小于八位  
            {
                tmpstr = str.Substring(strlen - 4, 4);//先截取最后四位数字  
                rstr = ConvertDigit(tmpstr);//转换最后四位数字  
                tmpstr = str.Substring(0, strlen - 4);//截取其余数字  
                //将两次转换的数字加上萬后相连接  
                rstr = String.Concat(ConvertDigit(tmpstr) + "萬", rstr);
                rstr = rstr.Replace("零萬", "萬");
                rstr = rstr.Replace("零零", "零");
            }
            else if (strlen <= 12)//数字长度大于八位，小于十二位  
            {
                tmpstr = str.Substring(strlen - 4, 4);//先截取最后四位数字  
                rstr = ConvertDigit(tmpstr);//转换最后四位数字  
                tmpstr = str.Substring(strlen - 8, 4);//再截取四位数字  
                rstr = String.Concat(ConvertDigit(tmpstr) + "萬", rstr);
                tmpstr = str.Substring(0, strlen - 8);
                rstr = String.Concat(ConvertDigit(tmpstr) + "億", rstr);
                rstr = rstr.Replace("零億", "億");
                rstr = rstr.Replace("零萬", "零");
                rstr = rstr.Replace("零零", "零");
                rstr = rstr.Replace("零零", "零");
            }
        }
        strlen = rstr.Length;
        if (strlen >= 2)
        {
            switch (rstr.Substring(strlen - 2, 2))
            {
                case "佰零": rstr = rstr.Substring(0, strlen - 2) + "佰"; break;
                case "仟零": rstr = rstr.Substring(0, strlen - 2) + "仟"; break;
                case "萬零": rstr = rstr.Substring(0, strlen - 2) + "萬"; break;
                case "億零": rstr = rstr.Substring(0, strlen - 2) + "億"; break;
            }
        }
        return rstr;
    }
    /// 转换数字（小数部分）  
    /// 需要转换的小数部分数字字符串  
    /// 转换成中文大写后的字符串  
    public string ConvertXiaoShu(string str)
    {
        int strlen = str.Length;
        string rstr;
        if (strlen == 1)
        {
            rstr = ConvertChinese(str) + "角";
            return rstr;
        }
        else
        {
            string tmpstr = str.Substring(0, 1);
            rstr = ConvertChinese(tmpstr) + "角";
            tmpstr = str.Substring(1, 1);
            rstr += ConvertChinese(tmpstr) + "分";
            rstr = rstr.Replace("零分", "");
            rstr = rstr.Replace("零角", "");
            return rstr;
        }
    }
    // 转换数字  
    // 转换的字符串（四位以内）  
    public string ConvertDigit(string str)
    {
        int strlen = str.Length;
        string rstr = "";
        switch (strlen)
        {
            case 1: rstr = ConvertChinese(str); break;
            case 2: rstr = Convert2Digit(str); break;
            case 3: rstr = Convert3Digit(str); break;
            case 4: rstr = Convert4Digit(str); break;
        }
        rstr = rstr.Replace("拾零", "拾");
        strlen = rstr.Length;
        return rstr;
    }
    /// 转换四位数字  
    public string Convert4Digit(string str)
    {
        string str1 = str.Substring(0, 1);
        string str2 = str.Substring(1, 1);
        string str3 = str.Substring(2, 1);
        string str4 = str.Substring(3, 1);
        string rstring = "";
        rstring += ConvertChinese(str1) + "仟";
        rstring += ConvertChinese(str2) + "佰";
        rstring += ConvertChinese(str3) + "拾";
        rstring += ConvertChinese(str4);
        rstring = rstring.Replace("零仟", "零");
        rstring = rstring.Replace("零佰", "零");
        rstring = rstring.Replace("零拾", "零");
        rstring = rstring.Replace("零零", "零");
        rstring = rstring.Replace("零零", "零");
        rstring = rstring.Replace("零零", "零");
        return rstring;
    }
    // 转换三位数字  
    public string Convert3Digit(string str)
    {
        string str1 = str.Substring(0, 1);
        string str2 = str.Substring(1, 1);
        string str3 = str.Substring(2, 1);
        string rstring = "";
        rstring += ConvertChinese(str1) + "佰";
        rstring += ConvertChinese(str2) + "拾";
        rstring += ConvertChinese(str3);
        rstring = rstring.Replace("零佰", "零");
        rstring = rstring.Replace("零拾", "零");
        rstring = rstring.Replace("零零", "零");
        rstring = rstring.Replace("零零", "零");
        return rstring;
    }
    /// 转换二位数字  
    public string Convert2Digit(string str)
    {
        string str1 = str.Substring(0, 1);
        string str2 = str.Substring(1, 1);
        string rstring = "";
        rstring += ConvertChinese(str1) + "拾";
        rstring += ConvertChinese(str2);
        rstring = rstring.Replace("零拾", "零");
        rstring = rstring.Replace("零零", "零");
        return rstring;
    }
    /// 将一位数字转换成中文大写数字  
    public string ConvertChinese(string str)
    {
        //"零壹贰叁肆伍陆柒捌玖拾佰仟萬億圆整角分"  
        string cstr = "";
        switch (str)
        {
            case "0": cstr = "零"; break;
            case "1": cstr = "壹"; break;
            case "2": cstr = "贰"; break;
            case "3": cstr = "叁"; break;
            case "4": cstr = "肆"; break;
            case "5": cstr = "伍"; break;
            case "6": cstr = "陆"; break;
            case "7": cstr = "柒"; break;
            case "8": cstr = "捌"; break;
            case "9": cstr = "玖"; break;
        }
        return (cstr);
    }
}