C#公历转农历算法

using System;
using System.Collections.Generic;
using System.Text;

namespace WindowsFormsApplication1
{
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×××
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", "十一", "腊" };

private static string[] WeekDay = { "日","一", "二", "三", "四", "五", "六" };
//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
,3402,3749,331177,1453,694,201326,2350,465197,3221,3402
,400202,2901,1386,267611,605,2349,137515,2709,464533,1738
,2901,330421,1242,2651,199255,1323,529706,3733,1706,398762
,2741,1206,267438,2647,1318,204070,3477,461653,1386,2413
,330077,1197,2637,268877,3365,531109,2900,2922,398042,2395
,1179,267415,2635,661067,1701,1748,398772,2742,2391,330031
,1175,1611,200010,3749,527717,1452,2742,332397,2350,3222
,268949,3402,3493,133973,1386,464219,605,2349,334123,2709
,2890,267946,2773,592565,1210,2651,395863,1323,2707,265877};
/// <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;
}

//×××
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";

 

#endregion
//计算星期
string week="星期"+WeekDay[(int)dtDay.DayOfWeek];
calendar +=" "+ week;
return calendar;
}

}
}