Question

How to get the name of the day of a given date in C

Answer 1

#include <stdio.h>
#include <stdbool.h>

bool IsLeapYear(unsigned int year) {
	return (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
}

int GetDayOfYear(unsigned int year, char month, char day) {
	unsigned short days[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

	if (IsLeapYear(year) && month >= 2)
		return days[month - 1] + day + 1;

	return days[month - 1] + day;
}

int main() {

	char* days[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };

	int dayOfYear = GetDayOfYear(2023, 5, 15);

	printf("%s", days[(dayOfYear - 1) % 7]);
}




/*
run:

Monday

*/

 

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