Calculate previous week's start and end date

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.

From stackoverflow

• 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.

• Using DayOfWeek would be a way of achieving this:

      DateTime date = DateTime.Now.AddDays(-7);
      while (date.DayOfWeek != DayOfWeek.Monday)
      {
          date = date.AddDays(-1);
      }
  
      DateTime startDate = date;
      DateTime endDate = date.AddDays(7);
  

• 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.

  Austin Salonen : To answer the question, startOfWeek should be named sundayOfLastWeek. "DateTime mondayOfLastWeek = date.AddDays(-(int)date.DayOfWeek - 6);"

  bstoney : Thanks for the correction Austin Salonen

  Henryk : Nice one liner approach. I think the following would then work regardless of which day its run on: mondayOfLastWeek = DateTime.Now.AddDays( -(int)DateTime.Now.DayOfWeek - 6 ); sundayOfLastWeek = DateTime.Now.AddDays(-(int)DateTime.Now.DayOfWeek);

• using Fluent DateTime http://fluentdatetime.codeplex.com/

          var dateTime = 1.Weeks().Ago();
          var monday = dateTime.Previous(DayOfWeek.Sunday);
          var sunday = dateTime.Next(DayOfWeek.Sunday);