/* week.c 05-02-2000 */

#include <stdio.h>
#include <stdlib.h>

/* True false constants*/
#define TRUE 1
#define FALSE 0

int main(void)
{	int	day			= 0,
		month		= 0,
		year 		= 0,
		day_of_week	= 0,
		leap_year	= 0;
		ret_val 	= 0;

	while ( ret_val != 3 )
	{ 	printf("Enter a date between 01:01:1800 - 31:12:1999 (DD:MM:YYYY) > ");
		scanf("%d:%d:%d",&day,&month,&year);
	}

	printf("Enter a date between 01:01:1800 - 31:12:1999 (DD:MM:YYYY) > ");
	scanf("%d:%d:%d",&day,&month,&year);

	/*Get last two digits of year and add a quater of it*/
	day_of_week = (year % 100) + ((year % 100) * 0.25);

	/*Add day of the month*/
	day_of_week += day;

	/*Check for leap year*/
	if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
		leap_year = TRUE;
	else
		leap_year = FALSE;

	/*Those months with a missing case have nothing added to them*/
	switch (month)
	{	case 1:
			if (leap_year == FALSE)
				day_of_week += 1;
			break;
		case 2:
			if (leap_year == TRUE)
				day_of_week += 3;
			else
				day_of_week += 4;
			break;
		case 3:
			day_of_week += 4;
			break;
		case 5:
			day_of_week += 2;
			break;
		case 6:
			day_of_week += 5;
			break;
		case 8:
			day_of_week += 3;
			break;
		case 9:
			day_of_week += 6;
			break;
		case 10:
			day_of_week += 1;
			break;
		case 11:
			day_of_week += 4;
			break;
		case 12:
    		day_of_week += 6;
			break;
	}

	/* Add 2 if year is between 1800 - 1899 */
	if ( year < 1900 )
		day_of_week += 2;

	day_of_week = day_of_week % 7;

	/* Find out what day of week it is */
	switch (day_of_week)
	{	case 1:
			printf("%d:%d:%d was a Sunday\n", day, month, year);
        	break;
		case 2:
			printf("%d:%d:%d was a Monday\n", day, month, year);
			break;
		case 3:
			printf("%d:%d:%d was a Tuesday\n", day, month, year);
			break;
		case 4:
			printf("%d:%d:%d was a Wednesday\n", day, month, year);
			break;
		case 5:
			printf("%d:%d:%d was a Thursday\n", day, month, year);
			break;
		case 6:
			printf("%d:%d:%d was a Friday\n", day, month, year);
			break;
		case 0:
            printf("%d:%d:%d was a Saturday\n", day, month, year);
            break;
	}
	return EXIT_SUCCESS;
}