Can DateTime spare a quarter?

Ok so this isn’t really very impressive for a blog post, but I am curious if anyone has a more sensible way to do this.

The DateTime struct understands, seconds, minutes, hours, days, months, years, etc. However, I find it kind of odd that the DateTime struct doesn’t understand “quarters”. Quarters of a year are a common concept in any finance application and unlike weeks they are not all the same length.

What I need to determine is the start and end dates of the quarter for the current date minus one month. There are a million ways I could do this:

1. I could just have a helper class with the 4 start date of the quarter and have it do comparisons. Seems a bit overkill to have a class.
2. I could just compare the DateTime.Month value to values 1, 4, 7, 10 to figure out which quarter I am in and then set the start and end dates. This is nice and simple.
3. Instead I did this:

//Get the previous month mod(3) (0,1,2) 
var monthInQuarter = (DateTime.Today.Month + 1) % 3;

//Set start and end dates
EndDate = DateTime.Today.AddDays(-(DateTime.Today.Day));

//Start date is the first day of the beginning of the quarter
StartDate = EndDate.AddMonths(-1*monthInQuarter).AddDays(-(EndDate.Day-1));

mmmmm… mod math ;-). Ok so it isn’t that cool, but I’m sure I’m going to need to use this again.

Chris

Edit: Fixed my total failure with brackets.