C#公历转农历算法

 
/// <summary>
/// LunDay 的摘要说明。
/// 用法说明
/// 直接调用即可,比较简单
/// </summary>
public class LunDay
{
    public LunDay()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }
    //天干
    private static string[] TianGan = { "甲","乙","丙","丁","戊","己","庚","辛","壬","癸" };

    //地支
    private static string[] DiZhi = { "子","丑","寅","卯","辰","巳","午","未","申","酉","戌","亥" };

    //十二生肖
    private static string[] ShengXiao = { "鼠","牛","虎","兔","龙","蛇","马","羊","猴","鸡","狗","猪" };

    //农历日期
    private static string[] DayName =   {"*","初一","初二","初三","初四","初五","初六","初七","初八","初九","初十","十一","十二","十三","十四","十五","十六","十七","十八","十九","二十","廿一","廿二","廿三","廿四","廿五","廿六","廿七","廿八","廿九","三十"};

    //农历月份
    private static string[] MonthName = { "*","正","二","三","四","五","六","七","八","九","十","腊" };

    //公历月计数天
    private static int[] MonthAdd = { 0,31,59,90,120,151,181,212,243,273,304,334 };
    //农历数据
    private static int[] LunarData = {2635,333387,1701,1748,267701,694,2391,133423,1175,396438,3402,3749,331177,1453,201326,2350,465197,3221,400202,2901,1386,267611,605,2349,137515,2709,464533,1738,330421,1242,2651,199255,1323,529706,3733,1706,398762,2741,1206,267438,2647,1318,204070,3477,461653,2413,330077,1197,2637,268877,3365,531109,2900,2922,398042,2395,1179,267415,2635,661067,398772,2742,330031,1611,200010,527717,1452,332397,3222,268949,3493,133973,464219,334123,2890,267946,2773,592565,1210,395863,2707,265877};
    /// <summary>
    /// 获取对应日期的农历
    /// </summary>
    /// <param name="dtDay">公历日期</param>
    /// <returns></returns>
    public string GetLunarCalendar(DateTime dtDay)
    {
        string sYear = dtDay.Year.ToString();
        string sMonth = dtDay.Month.ToString();
        string sDay = dtDay.Day.ToString();
        int year;
        int month;
        int day;
        try
        {
            year = int.Parse(sYear);
            month = int.Parse(sMonth);
            day = int.Parse(sDay);
        }
        catch
        {
            year = DateTime.Now.Year;
            month = DateTime.Now.Month;
            day = DateTime.Now.Day;
        }

        int nTheDate;
        int nIsEnd;
        int k,m,n,nBit,i;
        string calendar = string.Empty;
        //计算到初始时间1921年2月8日的天数：1921-2-8(正月初一)
        nTheDate = (year - 1921) * 365 + (year - 1921) / 4 + day + MonthAdd[month - 1] - 38;
        if ((year % 4 == 0) && (month > 2))
            nTheDate += 1;
        //计算天干，地支，月，日
        nIsEnd = 0;
        m = 0;
        k = 0;
        n = 0;
        while (nIsEnd != 1)
        {
            if (LunarData[m] < 4095)
                k = 11;
            else
                k = 12;
            n = k;
            while (n >= 0)
            {
                //获取LunarData[m]的第n个二进制位的值
                nBit = LunarData[m];
                for (i = 1; i < n + 1; i++)
                    nBit = nBit / 2;
                nBit = nBit % 2;
                if (nTheDate <= (29 + nBit))
                {
                    nIsEnd = 1;
                    break;
                }
                nTheDate = nTheDate - 29 - nBit;
                n = n - 1;
            }
            if (nIsEnd == 1)
                break;
            m = m + 1;
        }
        year = 1921 + m;
        month = k - n + 1;
        day = nTheDate;
        //return year+"-"+month+"-"+day;

        #region 格式化日期显示为三月廿四
        if (k == 12)
        {
            if (month == LunarData[m] / 65536 + 1)
                month = 1 - month;
            else if (month > LunarData[m] / 65536 + 1)
                month = month - 1;
        }

        //生肖
        calendar = ShengXiao[(year - 4) % 60 % 12].ToString() + "年 ";
        //天干
        calendar += TianGan[(year - 4) % 60 % 10].ToString();
        //地支
        calendar += DiZhi[(year - 4) % 60 % 12].ToString() + " ";

        //农历月
        if (month < 1)
            calendar += "闰" + MonthName[-1 * month].ToString() + "月";
        else
            calendar += MonthName[month].ToString() + "月";

        //农历日
        calendar += DayName[day].ToString() + "日";

        return calendar;

        #endregion
    }
}