Convert a date to a day of the week
[C++]
int XlWeekday(
long date,
int* day
);
An integer serial date value.
Pointer to a variable which will be filled with an integer between 1 (Monday) and 7 (Sunday).
1 if the function succeeds; 0 if it fails
This function calls Excel's WEEKDAY() function
with 2 as its second argument.
Header: xlldate.h