Date Arithmetic

[Gil]

I run a webserver on Win2k Server and program in vb.net.

I am trying to perform a calculation that results in two
weeks of data given any selected date that starts with
the Sunday of the selected date. In order to accomplish
this I need to perform some date arithmetic.

For instance, if a user enters 11/6/2003 (Thu), then I
want to generate data from 11/2/2003 to 11/15/2003. If I
choose 11/3/2003 (Mon), this too would generate 11/2/2003
to 11/15/2003. But if I choose 11/10/2003, then I would
generate 11/9/2003 to 11/22/2003.

To do this my plan was to convert a Date to Int, perform
arithmetic, then convert back to Date. What I envisioned
was something like this:

If Weekday(SelectedDate) > 1
Then StartDate = CDate(CInt(SelectedDate) - Weekday
(SelectedDate) + 1)
End If

EndDate = CDate(CInt(StartDate) + 13)

This does not seem to work. I have even tried to use
CType to coerce, unsucessfully.

Please help.
TIA,
Gil

[Jon Skeet [C# MVP]]

Gil <an*******@discussions.microsoft.com> wrote:

I run a webserver on Win2k Server and program in vb.net.

I am trying to perform a calculation that results in two
weeks of data given any selected date that starts with
the Sunday of the selected date. In order to accomplish
this I need to perform some date arithmetic.

For instance, if a user enters 11/6/2003 (Thu), then I
want to generate data from 11/2/2003 to 11/15/2003. If I
choose 11/3/2003 (Mon), this too would generate 11/2/2003
to 11/15/2003. But if I choose 11/10/2003, then I would
generate 11/9/2003 to 11/22/2003.

To do this my plan was to convert a Date to Int, perform
arithmetic, then convert back to Date. What I envisioned
was something like this:

I'd suggest using DateTime.DayOfWeek, and then DateTime.AddDays
appropriately depending on the retrieved day of the week.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
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