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.netvb.netdatedaysdate-difference

Get Date of Previous Monday

I'm trying to get the date of the monday in the current week. Is this close to correct?

Dim MondayOfCurrentWeek As Date = Date.Today - Date.Today.DayOfWeek + 1

As far as I understand it the AyOfWeek indexes are:

1 = Monday
2 = Tuesday
3 = Wednesday
4 = Thursday
5 = Friday
6 = Saturday
0 = Sunday

Hence if for example Date Today is a thursday I would get:

Dim MondayOfCurrentWeek As Date = Date - 4 + 1

which would be equal to 

Date - 3

and seems right to me.

Or am I totally off?

Solution

  • A very simple alternative approach, which while probably not as performant, but does avoid any arithmetic based errors:

    Dim monday As Date = Date.Today
While (monday.DayOfWeek <> DayOfWeek.Monday)
    monday = monday.AddDays(-1)
End While

    This could easily be extended out to a function to handle any day of the week. Unless this is a really high volume piece of code, performance will be fine.