How to Convert Gregorian Calendar into Lunar Calendar in c++

1. Algorithm for Converting Gregorian Calendar into Lunar Calendar

The conversion between Gregorian calendar and China lunar calendar is not a simple formula, but rather complicated, because the formula of the lunar calendar is quite complicated and is specified according to astronomical observation.

The common and simple algorithm for converting the solar calendar into the lunar calendar is the look-up table method. First of all, we should save the conversion information of Gregorian calendar lunar calendar: starting from any year, we should save the lunar calendar information of several years starting from this year (starting from 1900 in my C++ class). The idea of choosing a starting point is very important, which is also reflected in the following commandments and 24 solar terms. Think back, how do we usually convert the solar calendar into the lunar calendar? Is to consult the almanac, which contains the solar calendar and lunar calendar of every day. Just check it directly. So can we do the same thing? Sure, but it takes a lot of work to include daily information, so we should simplify this information. How to simplify it?

In fact, only two pieces of information are needed to save information for one year: (1) the size of each month in the lunar calendar; (2) Whether there are leap months, leap months and leap month sizes this year. It is enough to use an integer to store this information. The specific method is to use a digit to represent the size of a month, where the big month is 1 and the small month is 0, so that the digit 12 is used, and the lower four digits are used to represent leap months, and no leap months are 0. For example, the information data in 2000 is 0x0c960, which is 11kloc-0/05438+000000 when converted into binary, that is,1,2,5,8,65400. The lunar calendar information data of 200 1 year is 0x0d954, where 4 represents leap April of that year, and the month size information is 0x0d95, specifically, 1, 2, 4, 5, 8, 10, 12 months old, and the rest months are smaller. In this way, you can use an array to store this information. In my C++ class, I use the array m_lunarInfo to store this information.

The following is the specific algorithm for converting Gregorian calendar into lunar calendar:

(1) Calculates the number of days from the required time to the first day of the first month of the starting year.

(2) From the beginning of the year, subtract the number of days in each month until there are no days in the next month. So far, how many years has the subscript of m_lunarInfo been subtracted? Add this subscript to the starting year to get the lunar year, and then see how many months have been subtracted. If there is no leap month this year or the leap month is still behind, you can directly take the lunar month. If it is a month after a leap month, this month is a leap month. The rest of the days are lunar calendar days. (The specific implementation has been improved. )

2. It is helpful for Taylor formula to calculate the week skillfully.

In applied mathematics, there is a formula to calculate the day of the week, which is Taylor formula. The formula is as follows: w = [c ÷ 4]-2c+y+[y ÷ 4]+[26 (m+1) ÷10]+d-1,where w is the number of weeks of the request date. If the number is greater than (less than) 7, subtract (add) multiples of 7 until the remainder is less than 7. Where c represents the first two digits of the year, y represents the last two digits, m represents the number of months, and d represents the number of days. The square brackets [] indicate that the figures in brackets are rounded. It is also important to note that if the month is 1 or February, it should be regarded as 13 or 14 of the previous year, that is, the range of m in the formula is from 3 to 14, not from 1 to 12.

3. Discipline of cadres and party branches

There are ten heavenly stems, namely A, B, C, D, E, Ji, G, Xin, Ren and Gui, and twelve earthly branches, namely Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai. The ancients paired them in a certain order, without repetition, from Jiazi to Guihai * * * 60 pairs, called Sixty Jiazi. The ancient Chinese used these 60 pairs of branches to represent the serial numbers of years, months, days and hours, and this is the discipline of branches and branches.

0 jiazi

1 ugly B.

2 bingyin

3 ding Mao

4 Chen Wu

5-episode episode

6 Wu Geng

7 Xin Wei

8 Ren Shen

9 Gui You 10 JOE

1 1 yihai

12 ice posture

13 Ding Chou

14 wuyin

15 Trade Fair

16 Chen Geng

17 symplectic set

18 Renwu

19 Guiwei 20 Shen Jia

2 1 Yiyou

22 Xu Bing

23 Dinghai

24 abital

25 ugly

26 Geng Yin

27 Xin Mao

28 Renchen

There are 30 Wu Jia in 29 countries.

3 1 B Wei

32 Shen Bing

33 Ding You

34 reform movement

35 jihai

36 gengzi

37 Xin Chou

38 people drink

39 Gui Mao 40 Chen Jia

4 1 B Yes

42 Wu Bing

43 Ding Wei

44 Wu Shen

45 Ji You

46 Geng Xu

47 Xinhai

48 Renzi

49 Guichou 50 Good News

5 1 Mao Yi

52 Chen Bing

53 butyl

54 55

55 didn't

56 Geng Shen

57 Xin you

Renxu 58 Hao

The principle of representing the year, month and day is the same, that is, the number of years, months and days from the year, month and day to the starting year, month and day, plus the serial numbers of the stems and branches of the starting year, month and day in the above table, the serial numbers of the stems and branches take the modulus 10, and the serial numbers of the stems and branches take the modulus/kloc-0. For example, beginning of spring after 1900 is the year of boxer. As can be seen from the above table, the year of Gengzi is the 36th year in sixty years, so the number of years from m_year to 1900 is m_year- 1900+36- 1 (if the month is m_month, similarly, we can get the representation of month and day. Finally, according to the solar term (beginning of spring), February of the Gregorian calendar should be adjusted. According to the date of the first solar term of each month, the monthly dry branch representation is adjusted, and the specific situation is detailed in the source program.

The ancients divided a day and night into twelve hours according to the time when the sun rose, with the twelve earthly branches as the code. If m_hour is used to represent the current hours of the Gregorian calendar (twenty-four notation), (m_hour+ 1)/2 will get the earthly branch representation of time (in fact, it is the serial number of earthly branches).

4. 24 solar terms

In essence, solar terms belong to the solar calendar. From the astronomical point of view, the 24 solar terms are divided into 24 equal parts according to the 360-degree revolution of the earth around the sun (ecliptic), and the spring is divided into zero points. The two bisectors are separated by 15 degrees, and each bisector has a proper name, which contains the significance of climate change, phenological characteristics and crop growth. The twenty-four solar terms are beginning of spring, rain, surprise, vernal equinox, Qingming, Grain Rain, Long Summer, Xiaoman, Mangzhong, Summer Solstice, Slight Summer, Great Summer, beginning of autumn, Early Summer, White Dew, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Winter Solstice, Slight Cold and Severe Cold. In the above order, all the single rooms are solar terms, usually called solar terms, while the double rooms are "neutral gas", referred to as "gas" for short, collectively referred to as solar terms. Now it is generally called twenty-four solar terms.

Since ancient times, the calculation of solar terms is a flat solar term obtained by dividing a year into 24 equal parts. In the old calendar, 24 Qi is calculated by the method of leveling Qi, which divides a tropical year into 24 equal parts, and arranges solar terms and neutral Qi in turn at equal intervals from winter solstice, so the degree of the sun running in Qi is not equal. The new calendar is calculated by the constant space method, which divides the degrees of sundays on the ecliptic into 24 parts. When the sun travels to a certain vernal equinox, it is set as the date of a solar term. Because the apparent motion of the sun is uneven, the time interval between solar terms is also unequal. However, whether it is the new calendar or the old calendar, the solstice in winter is the first of the twenty-four qi, so the difference between them is the biggest in the spring and autumn equinox. Why do traditional chroniclers in China know how to calculate the gas, but they are used to recording calendars with the gas? This is mainly because the average gas is easy to calculate, because under this method, the interval between each solar term and solar term or between gas and gas is fixed at 30 days, 5 hours and 2 quarters.

In this C++ class, the calculation of 24 solar terms is realized by using a simple average solar term algorithm. The array sTermInfo is used to record the minutes of each solar term from slight cold, and the function intstern (int y, int n) is used to get a day in the month where the nth solar term is located (n counts from slight cold 0). Because precession and nutation are not considered, the accuracy is not very high.