Calculate previous week's start and end date

Question

What is the best way to calculate the previous week's start and end date in C#? I.e. today 18 March would result in 9 March (Monday last week) and 15 March (Sunday last week).

I have seen this done with DayOfWeek and a switch statement to work out an offset but was wondering whether there is a more elegant way.

Answer 1

You can skip the while loop and use

DateTime mondayOfLastWeek = date.AddDays( -(int)date.DayOfWeek - 6 ); 

This assumes you're using Monday as the first day of the week.

Answer 2

DayOfWeek weekStart = DayOfWeek.Monday; // or Sunday, or whenever DateTime startingDate = DateTime.Today;  while(startingDate.DayOfWeek != weekStart)     startingDate = startingDate.AddDays(-1);  DateTime previousWeekStart = startingDate.AddDays(-7); DateTime previousWeekEnd = startingDate.AddDays(-1); 

Read: Backtrack one day at a time until we're at the start of this week, and then subtract seven to get to the start of last week.