中文数字大小写转阿拉伯数字

目前只支持”万“以下的转换。

private static string GetNumber4Chinese(string str)
        {
            string istr = "0";
            string cstr = string.Empty;
            string nstr = string.Empty;
            for (int i = 0; i < str.Length; i++)
            {
                cstr = str.Substring(i, 1);
                nstr = (i < str.Length - 1) ? str.Substring(i + 1, 1) : "个";

                switch (cstr)
                {
                    case "一":
                    case "壹":
                        istr = (Convert.ToInt64(istr) + 1 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "二":
                    case "两":
                    case "贰":
                        istr = (Convert.ToInt64(istr) + 2 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "三":
                    case "叁":
                        istr = (Convert.ToInt64(istr) + 3 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "四":
                    case "肆":
                        istr = (Convert.ToInt64(istr) + 4 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "五":
                    case "伍":
                        istr = (Convert.ToInt64(istr) + 5 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "六":
                    case "陆":
                        istr = (Convert.ToInt64(istr) + 6 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "七":
                    case "柒":
                        istr = (Convert.ToInt64(istr) + 7 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "八":
                    case "捌":
                        istr = (Convert.ToInt64(istr) + 8 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    case "九":
                    case "玖":
                        istr = (Convert.ToInt64(istr) + 9 * GetBaseNumber4ChineseUnit(nstr)).ToString();
                        break;
                    default:
                        if (str.Length < 2)
                        {
                            istr = GetBaseNumber4ChineseUnit(cstr).ToString();
                        }
                        else if (str.Length == 2 && (str.StartsWith("十") || str.StartsWith("拾")))
                        {
                            return (10 + Convert.ToInt64(GetNumber4Chinese(nstr))).ToString();
                        }
                        break;
                }
            }
            return istr;
        }

        private static int GetBaseNumber4ChineseUnit(string str)
        {
            int ibase = 0;
            string cstr = "0";
            for (int i = 0; i < str.Length; i++)
            {
                cstr = str.Substring(i, 1);
                switch (cstr)
                {
                    case "万":
                        ibase = 10000;
                        break;
                    case "千":
                        ibase = 1000;
                        break;
                    case "百":
                        ibase = 100;
                        break;
                    case "十":
                        ibase = 10;
                        break;
                    case "个":
                        ibase = 1;
                        break;
                }
            }
            return ibase;
        }