Code chuyển từ lịch dương sang lịch âm:

#include<stdio.h>

#include<conio.h>

#include<Math.h>

//Chuyen doi ngay

//Lay Ngày Julius

long getJulius(int intNgay, int intThang, int intNam)

{

int a, y, m, jd;

a = (int)((14 - intThang) / 12);

y = intNam + 4800 - a;

m = intThang + 12 * a - 3;

jd = intNgay + (int)((153 * m + 2) / 5) + 365 * y + (int)(y / 4) - (int)(y / 100) + (int)(y / 400) - 32045;

if (jd < 2299161)

{

jd = intNgay + (int)((153 * m + 2) / 5) + 365 * y + (int)(y / 4) - 32083;

}

return jd;

}

//Hàm chuyên ngày Julius sang ngày thuong

int toDate(long jd){

int a, b, c, d, e, m;

int day, month, year;

if (jd > 2299160)

{

// After 5/10/1582, Gregorian calendar

a = jd + 32044;

b = (int)((4 * a + 3) / 146097);

c = a - (int)((b * 146097) / 4);

}

else

{

b = 0;

c = jd + 32082;

}

d = (int)((4 * c + 3) / 1461);

e = c - (int)((1461 * d) / 4);

m = (int)((5 * e + 2) / 153);

day = e - (int)((153 * m + 2) / 5) + 1;

month = m + 3 - 12 * (int)(m / 10);

year = b * 100 + d - 4800 + (int)(m / 10);

}

// Tinh ngay Soc

int getNewMoonDay(int k){

float PI = 3.14;

double T, T2, T3, dr, Jd1, M, Mpr, F, C1, deltat, JdNew;

T = k / 1236.85;

T2 = T * T;

T3 = T2 * T;

dr = PI / 180;

double timeZone = 7.0;

Jd1 = 2415020.75933 + 29.53058868 * k + 0.0001178 * T2 - 0.000000155 * T3;

// Mean new moon

Jd1 = Jd1 + 0.00033 * sin((166.56 + 132.87 * T - 0.009173 * T2) * dr);

// Sun's mean anomaly

M = 359.2242 + 29.10535608 * k - 0.0000333 * T2 - 0.00000347 * T3;

// Moon's mean anomaly

Mpr = 306.0253 + 385.81691806 * k + 0.0107306 * T2 + 0.00001236 * T3;

// Moon's argument of latitude

F = 21.2964 + 390.67050646 * k - 0.0016528 * T2 - 0.00000239 * T3;

C1 = (0.1734 - 0.000393 * T) * sin(M * dr) + 0.0021 * sin(2 * dr * M);

C1 = C1 - 0.4068 * sin(Mpr * dr) + 0.0161 * sin(dr * 2 * Mpr);

C1 = C1 - 0.0004 * sin(dr * 3 * Mpr);

C1 = C1 + 0.0104 * sin(dr * 2 * F) - 0.0051 * sin(dr * (M + Mpr));

C1 = C1 - 0.0074 * sin(dr * (M - Mpr)) + 0.0004 * sin(dr * (2 * F + M));

C1 = C1 - 0.0004 * sin(dr * (2 * F - M)) - 0.0006 * sin(dr * (2 * F + Mpr));

C1 = C1 + 0.0010 * sin(dr * (2 * F - Mpr)) + 0.0005 * sin(dr * (2 * Mpr + M));

if (T < -11)

{

deltat = 0.001 + 0.000839 * T + 0.0002261 * T2 - 0.00000845 * T3 - 0.000000081 * T * T3;

}

else

{

deltat = -0.000278 + 0.000265 * T + 0.000262 * T2;

}

JdNew = Jd1 + C1 - deltat;

return (int)(JdNew + 0.5 + timeZone / 24);

}

//Tính toa do mat troi

int getSunLongitude(int jdn){

double timeZone = 7.0;

float PI = 3.14;

double T, T2, dr, M, L0, DL, L;

// Time in Julian centuries from 2000-01-01 12:00:00 GMT

T = (jdn - 2451545.5 - timeZone / 24) / 36525;

T2 = T * T;

// degree to radian

dr = PI / 180;

// mean anomaly, degree

M = 357.52910 + 35999.05030 * T - 0.0001559 * T2 - 0.00000048 * T * T2;

// mean longitude, degree

L0 = 280.46645 + 36000.76983 * T + 0.0003032 * T2;

DL = (1.914600 - 0.004817 * T - 0.000014 * T2) * sin(dr * M);

DL = DL + (0.019993 - 0.000101 * T) * sin(dr * 2 * M) + 0.000290 * sin(dr * 3 * M);

L = L0 + DL; // true longitude, degree

L = L * dr;

// Normalize to (0, 2*PI)

L = L - PI * 2 * (int)(L / (PI * 2));

return (int)(L / PI * 6);

}

// Tìm ngày bat dau tháng 11 am lich

int getLunarMonthll(int intNam){

double k, off, nm, sunLong;

off = getJulius(31, 12, intNam) - 2415021;

k = (int)(off / 29.530588853);

nm = getNewMoonDay((int)k);

// sun longitude at local midnight

sunLong = getSunLongitude((int)nm);

if (sunLong >= 9)

{

nm = getNewMoonDay((int)k - 1);

}

return (int)nm;

}

//Xác dinh thang nhuan

int getLeapMonthOffset(double a11){

double last, arc;

int k, i;

k = (int)((a11 - 2415021.076998695) / 29.530588853 + 0.5);

last = 0;

// We start with the month following lunar month 11

i = 1;

arc = getSunLongitude((int)getNewMoonDay((int)(k + i)));

do

{

last = arc;

i++;

arc = getSunLongitude((int)getNewMoonDay((int)(k + i)));

} while (arc != last && i < 14);

return i - 1;

}

//Doi ra ngay am-duong

int convertSolar2Lunar(int intNgay, int intThang, int intNam){

double dayNumber, monthStart, a11, b11, lunarDay, lunarMonth, lunarYear;

//double lunarLeap;

int k, diff;

dayNumber = getJulius(intNgay,intThang,intNam);

k = (int)((dayNumber - 2415021.076998695) / 29.530588853);

monthStart = getNewMoonDay(k + 1);

if (monthStart > dayNumber)

{

monthStart = getNewMoonDay(k);

}

a11 = getLunarMonthll(intNam);

b11 = a11;

if (a11 >= monthStart)

{

lunarYear = intNam;

a11 = getLunarMonthll(intNam - 1);

}

else

{

lunarYear = intNam + 1;

b11 = getLunarMonthll(intNam + 1);

}

lunarDay = dayNumber - monthStart + 1;

diff = (int)((monthStart - a11) / 29);

//lunarLeap = 0;

lunarMonth = diff + 11;

if (b11 - a11 > 365)

{

int leapMonthDiff = getLeapMonthOffset(a11);

if (diff >= leapMonthDiff)

{

lunarMonth = diff + 10;

if (diff == leapMonthDiff)

{

//lunarLeap = 1;

}

}

}

if (lunarMonth > 12)

{

lunarMonth = lunarMonth - 12;

}

if (lunarMonth >= 11 && diff < 4)

{

lunarYear -= 1;

}

int Ngay = int(lunarDay);

int Thang = int(lunarMonth);

int Nam = int(lunarYear);

return printf("\n Ngay am: %d/%d/%d",Ngay, Thang, Nam);

}

main()

{

int intNgay, intThang, intNam;

printf("\n Nhap vao ngay: ");

scanf("%d",&intNgay);

printf("\n Nhap vao thang: ");

scanf("%d",&intThang);

printf("\n Nhap vao nam: ");

scanf("%d",&intNam);

convertSolar2Lunar(intNgay,intThang,intNam);

getch();

}