void GetMonthBoundaries(int month, int year, out DateTime firstDayOfMonth,
out DateTime lastDayOfMonth)
{
// how to get the 1st day of the month? it's always day 1, so this is simple enough
DateTime first = new DateTime(year, month, 1);
// how do we get the last day of the month when months have
// varying numbers of days?
//
// adding 1 month to "first" gives us the 1st day of the following month
// then if we subtract one second from that date, we get a DateTime that
// represents the last second of the last day of the desired month
// example: if month = 2 and year = 2011, then
// first = 2011-02-01 00:00:00
// last = 2011-02-28 23:59:59
DateTime last = first.AddMonths(1).AddSeconds(-1);
// if you're not concerned with time of day in your DateTime values
// and are only comparing days, then you can use the following line
// instead to get the last day:
//
// DateTime last = first.AddMonths(1).AddDays(-1);
// example: if month = 2 and year = 2011, then
// first = 2011-02-01 00:00:00
// last = 2011-02-28 00:00:00
firstDayOfMonth = first;
lastDayOfMonth = last;
}
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