中文简体数字转换为阿拉伯数字（大家帮看下有没有反例，并提出改进意见）

这是界面！，以下为代码！大家帮忙找下反例，能指出程序的不足就更好了，小弟多多努力！

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;

namespace ChinesNumToint
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnChange_Click(object sender, EventArgs e)
        {
            //零，一，二，三，四，五，六，七，八，九，十，百，千，万
            //一万一千一百一十一
            //一万零一
            //二零零二
            //五百六十万
            //
           string CNum= txtCNum.Text;
            if (IsCNUM(CNum))
            {
                txtANum.Text = "中文数字有误";
            }
            else if(CNum.Length>8)
            {
                txtANum.Text = "数太大了，哥萎了！";
            }
            else
            {
                txtANum.Text = ToNumAll(txtCNum.Text).ToString();
            }
            
        }
        /// <summary>
        /// 转换9999及以下的数字
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        private double  ToNum1(string str)
        {
            char[] cNums=new char[7];
            cNums[1]='千';
            cNums[3] = '百';
            cNums[5] = '十';
            if ((!str.Contains('千'))&&(!str.Contains('百'))&&(!str.Contains('十')))
            {
                if (str.Length==1)
                {
                    cNums[0]='零';
                cNums[2] = '零';
                cNums[4] = '零';
                cNums[6] = str[0];
                }
                else if (str.Length==2)
                {
                    cNums[0] = '零';
                    cNums[2] = '零';
                    cNums[4] = str[0];
                    cNums[6] = str[1];
                }
                else if(str.Length==3)
                {
                    cNums[0] = '零';
                    cNums[2] = str[0];
                    cNums[4] = str[1];
                    cNums[6] = str[2];
                }
                else
                {
                    cNums[0] = str[str.Length-4];
                    cNums[2] = str[str.Length-3];
                    cNums[4] = str[str.Length-2];
                    cNums[6] = str[str.Length-1];
                }
                
            }
            else
            {
                if (str.Contains('千'))
                {
                    cNums[0] = str[str.IndexOf('千') - 1];
                }
                else
                {
                    cNums[0] = '零';
                }
                if (str.Contains('百'))
                {
                    cNums[2] = str[str.IndexOf('百') - 1];
                }
                else
                {
                    cNums[2] = '零';
                }
                if (str.Contains('十'))
                {
                    cNums[4] = str[str.IndexOf('十') - 1];
                }
                else
                {
                    cNums[4] = '零';
                }
                if (str[str.Length - 1] == '千' || str[str.Length - 1] == '百' || str[str.Length - 1] == '十')
                {
                    cNums[6] = '零';
                }
                else
                {
                    cNums[6] = str[str.Length - 1];
                }
            }
            return 1000 * CharToNum(cNums[0]) + 100 * CharToNum(cNums[2]) +10* CharToNum(cNums[4]) + CharToNum(cNums[6]);
            
        }
        /// <summary>
        /// 将单个中文数字转换为阿拉伯数字
        /// </summary>
        /// <param name="achar"></param>
        /// <returns></returns>
        private int CharToNum(char achar)
        {
            switch (achar)
            {
                case '零':
                    return 0;
                case '一':
                    return 1;
                case '二':
                    return 2;
                case '三':
                    return 3;
                case '四':
                    return 4;
                case '五':
                    return 5;
                case '六':
                    return 6;
                case '七':
                    return 7;
                case '八':
                    return 8;
                case '九':
                    return 9;
                default:
                    return -1;
            }
        }
        /// <summary>
        /// 判断是否包含非中文数字类字符
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        private bool IsCNUM(string str)
        {
            return Regex.IsMatch(str,@"[^'零','一','二','三','四','五','六','七','八','九','十','百','千','万'].");
        }
        /// <summary>
        /// 转换9999万9999以内的数字
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        private int ToNumAll(string str)
        {
            if (str.Contains('万'))
            {
                string str1 = str.Substring(0, str.IndexOf('万'));
                string str2 = str.Substring(str.IndexOf('万')+1);
                return ToNum1(str1) * 10000 + ToNum1(str2);
            }
            else if(str.Length>4)
            {
                string str1 = str.Substring(0, str.Length - 4);
                string str2 = str.Substring(str.Length - 4);
                return ToNum1(str1) * 10000 + ToNum1(str2);
            }
            else
            {
                return ToNum1(str);
            }
        }
    }
}