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Club Amiga de Montreal - CAM
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463.lha
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Date_routines
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datename.c
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1991-01-04
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955b
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38 lines
/*****
datename()
This function returns the day of the week for a date. It is based
on Zeller's Congruence.
Argument list: int month the month
int day the day
int year the year
Return value: char * a pointer to the day of the week
*****/
char *datename(int day, int month, int year)
{
static char *days[] = {"Sun.", "Mon.", "Tues", "Wed.",
"Thur", "Fri.", "Sat.", "Sun."};
int index;
if (year < 100) /* If century is missing */
year += 1900;
if (month > 2) { /* Everything is from February */
month -= 2;
} else {
month += 10;
year--;
}
index = ((13 * month - 1) / 5) + day + (year % 100) + ( (year % 100) / 4)
+ ((year / 100) / 4) - 2 * (year / 100) + 77;
index = index - 7 * (index / 7);
return days[index];
}