Well, I don't know about the logic of the structure, but if you ask a friend
what the date is one month from today, they would say January 21.  Seems
reasonable that DateTime would respond the same.

The problem with datetime calculations is, how do you know how many days to
add?  Do you work with the number of days in the current month, or next
month.  Hard to make that determination.

Hi,

You are adding which month?  and with what criteria?

I find the selected behavior increment the month in 1 is ok.

Now, a good question, what happen when you do new DateTime(2005, 1,
30).AddMonths(1) ?
 Answer: you get 2/28/2005

cheers,

If you want the last day of the month its better take one day off the month
plus.

ie.  To get the last day of this month do

DateTime lastday = DateTime.Parse((DateTime.Now.Month+1) + "\\1\\" +
DateTime.Now.Year).AddDays(-1);

of course you need a condition if its december.

Why would it? It's thirty days into November, plus a month. For me,
that should return thirty days into December.

It gets more tricky when you add a month from the 30th of January, and
unfortunately the behaviour isn't actually specified in the docs as far
as I can see. I'd expect it to give February 28th (or 29th for a leap
year), that being the closest to February 30th which is actually
possible. I don't see that there's any ambiguity in your situation
though.

WOW! I knew this would get some interesting responses.

I asked several people today the following questions
1 - What is the date 1 month from today. Everyone answered 1/21
2 - What is the date 1 month from 1/31. Some answered 3/2 and others said
3/3. One said 2/28
3 - What is one month from 11/30 - I got a split - 12/30 & 12/31. (This
question was asked last so some people started thinking)

It's interesting how people think. In all cases when asking what is the date
from any date that is not the end of the month everyone answers the same day
in the next month 1/15 -> 2/15

I understand how AddMonths work I just wasn't exactly sure if that was
intended.

Anyway, it was an interesting discussion.
-Joe