• Home
 · 
• Math/Dates
 · 
• Mathematically calculate the day of the week.

Mathematically calculate the day of the week.

Mathematically calculate the day of the week.

Rate Mathematically calculate the day of the week.

• 1
• 2
• 3
• 4
• 5

(1(1 Vote))

    Dim DOW As Integer
    DOW = DayOfWeek(2000, 11, 22)   ' November 22, 2000
    Select Case DOW
        Case 0:
            Print "Sunday"
        Case 1:
            Print "Monday"
        Case 2:
            Print "Tuesday"
        Case 3:
            Print "Wednesday"
        Case 4:
            Print "Thursday"
        Case 5:
            Print "Friday"
        Case 6
            Print "Saturday"
        Case Else
            Print "Error"
    End Select
End Sub

Private Function DayOfWeek(y As Integer, m As Integer, d As Integer)
    ' Programmatically calculate the day of the week from a given date.
    
    ' DOW = ([23m/9] + d + 4 + z + [z/4] - [z/100] + [z/400] - 2 (if m>=3)) mod 7
    '
    ' y is the 4 digit year
    ' m is the month
    ' d is the day.
    ' z = y - 1 (if m <  3)
    '   = y     (if m >= 3)
    ' A mod B means take the reminder of A / B.
    '
    ' Sunday = 0, Monday = 1, etc.
    '
    If m < 3 Then
       y = y - 1
    Else
       y = y - 2
    End If
    
    DayOfWeek = ((23 * m / 9 + d + 4 + y + (y / 4) - (y / 100) + (y / 400)) Mod 7)
End Function