将日期转为中文字符的类

正在做一个东西，要求从15，18位的身份证上取下出生日期，形式为19800825,然后分开年月日转为中文：一九八O、八、二十五，下面是源代码

 

/**/ /// <summary>
/// Summary description for NumToChinese
/// </summary>
/// <summary>

/// 将日期转换为中文形式,日期是从身份证上取下的,暂不作数据有效性验证,形式为年：2004 月03 日26
/// 从身份证取出生日期的程序就不写了
/// Joeliang

/// 2007.7.5

/// </summary>
using System;
using System.Collections.Generic;
using System.Text;

public class NumToChinese
{
 private const string chinese = "○一二三四五六七八九";
   
    public static string ConvertYear(string year)
    {
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < year.Length; i++)
        {
            result.Append(chinese[int.Parse(year[i].ToString())]);
        }
        return result.ToString();
    }

    //从身份证取下来的月，例如01,10,12
    public static string ConvertMonth(string month)
    {
        StringBuilder result = new StringBuilder();
       
        if (month[0].ToString() == "0") //如果是1-9月份
        {
            result.Append(chinese[int.Parse(month[1].ToString())]);
        }
        else
            if (month == "10") //如果是10月份
            {
                result.Append("十");
            }
            else                        //如果是11,12月份
            {
                result.Append("十");
                result.Append(chinese[int.Parse(month[1].ToString())]);
            }

        return result.ToString();
    }

    //从身份证取下来的日，例如01,08,10,22
    public static string ConvertDay(string day)
    {
        StringBuilder result = new StringBuilder();

        if (day[0].ToString() == "0") //如果是个位数
        {
            result.Append(chinese[int.Parse(day[1].ToString())]);
        }
        else
            if (day[1].ToString() == "0") //如果是10，20，30
            {
                if(day[0].ToString() == "1") //如果是10
                {
                }
                else   //如果是20,30
                {
                    result.Append(chinese[int.Parse(day[0].ToString())]);
                }
                result.Append("十");
            }
            else                          //如果是11,25,31
            {
                if(day[0].ToString() == "1") //如果是11-19
                {
                }
                else              //如果是21-29,31
                {
                    result.Append(chinese[int.Parse(day[0].ToString())]);
                }
                result.Append("十");
                result.Append(chinese[int.Parse(day[1].ToString())]);
            }

        
        return result.ToString();
    }

    
}