Get the Monday and Sunday for a certain DateTime in C#

Question

I have a for example the date "2010-11-09, Thuesday"

Now I want to get the datetime of the Monday and Sunday wherein lies the above stated date.

How would you do that?

Answer 1

This is probaly what you're after:

 DateTime date = DateTime.Today;

 // lastMonday is always the Monday before nextSunday.
 // When date is a Sunday, lastMonday will be tomorrow.     
 int offset = date.DayOfWeek - DayOfWeek.Monday;     
 DateTime lastMonday = date.AddDays(-offset);
 DateTime nextSunday = lastMonday.AddDays(6);

Edit: since lastMonday is not always what the name suggests (see the comments), the following one-liner is probably more to the point:

 DateTime nextSunday = date.AddDays(7 - (int) date.DayOfWeek);