How to use C language for 12 constellation?

1) Set the array a[2] to store the month and day, and analyze it from the perspective of rationality.

Month a[0]∈[ 1, 12], a[ 1], that is, the date is determined according to a[0], and a[0] is 2, 4, 6, 9,1/kloc-0.

When a[0] is 2, a[ 1] cannot exceed 29. If you enter 29, you need to subtract 1 (as the basis for constellation calculation of later date difference).

2) The first function, int sum_day (int* a), takes the input just now as a formal parameter, calculates that M days of n months are K days of this year according to a certain formula, and then returns this date.

3) Because every constellation is 30 days apart (according to February 28th). Let's assume that this number of days is returned by K, and then discuss it by category.

The first one, K.

The second switch ((k- 19)/30) {

Case 0: Water bottle

Case 1: Pisces

........