Question

Here is my code:

DateTime startDate = Convert.ToDateTime( orderDate ).AddMonths(-1);
DateTime endDate = Convert.ToDateTime( orderDate );

orderDate is a valid date I pass in.

How do I always guarantee startDate is the first day of the previous month for orderDate?
How do I always guarantee endDate is the last day of the month for orderDate?

Example:

orderDate = 5/4/2012

I want startDate to be 4/1/2012 (or 04/1/2012 whichever is default)
I want endDate to be 4/30/2012

How can I acheive this?

Answer 1

DateTime startDate = Convert.ToDateTime( orderDate ).AddMonths(-1);
// set to first of month
startDate = startDate.AddDays(1-startDate.Day);

// Set end date to last of month, which is one day before first of next month
DateTime endDate = startDate.AddMonths(1).AddDays(-1);