I would like the function to return an array of strings where each date is reprsented as "13/11" or any other format from where i can pull both the date and month.
Maybe it would look something like this:
char** get_dates_from_year_and_week(int year, int week) {
//Magic happens
return arr
}
get_dates_from_year_and_week(2021, 45);
//Would return ["08/11", "09/11", 10/11", "11/11", "12/11", "13/11", "14/11"];
How could this possible be obtained using c? Any library is welcome.
CodePudding user response:
To covert the year/week/(day-of-the-week) to a year/month/day, find the date of the first Monday of the year as ISO 8601 week-of-the-year begins on a Monday. Then add week*7
days to that. Use mktime()
to determine day-of the-week (since Sunday) and to bring an out-of-range date into its primary range.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
typedef struct {
int year, month, day;
} ymd;
typedef struct {
int year, week, dow; // ISO week-date: year, week 1-52,53, day-of-the-week 1-7
} ISO_week_date;
int ISO_week_date_to_ymd(ymd *y, const ISO_week_date *x) {
// Set to noon, Jan 4 of the year.
// Jan 4 is always in the 1st week of the year
struct tm tm = {.tm_year = x->year - 1900, .tm_mon = 0, .tm_mday = 4,
.tm_hour = 12};
// Use mktime() to find the day-of-the week
if (mktime(&tm) == -1) {
return -1;
}
// Sunday to Jan 4
int DaysSinceSunday = tm.tm_wday;
// Monday to Jan 4
int DaysSinceMonday = (DaysSinceSunday (7 - 1)) % 7;
tm.tm_mday = (x->dow - 1) (x->week - 1) * 7 - DaysSinceMonday;
if (mktime(&tm) == -1) {
return -1;
}
y->year = tm.tm_year 1900;
y->month = tm.tm_mon 1;
y->day = tm.tm_mday;
return 0;
}
"array of strings" --> leave that part for OP to do.