Question

How do I find the start of the week (both Sunday and Monday) knowing just the current time in C#?

Something like:

DateTime.Now.StartWeek(Monday); 

Answer 1

Use an extension method:

public static class DateTimeExtensions {     public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)     {         int diff = (7 + (dt.DayOfWeek - startOfWeek)) % 7;         return dt.AddDays(-1 * diff).Date;     } } 

Which can be used as follows:

DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Monday); DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Sunday);