[thechat] Visual Basic Help? SHIFT key

[Syed Zeeshan Haider]

Hello Everybody,
I need some help from Visual Basic experts here.
Here is a code from MSDN library:

<Visual Baisc>

Private Sub Form_MouseDown(Button As Integer, _
      Shift As Integer, X As Single, Y As Single)
   ShiftTest = Shift And 7               'needs explanation
   Select Case ShiftTest
      Case 1 ' or vbShiftMask
         Print "You pressed the SHIFT key."
      Case 2 ' or vbCtrlMask
         Print "You pressed the CTRL key."
      Case 4 ' or vbAltMask
         Print "You pressed the ALT key."
      Case 3
         Print "You pressed both SHIFT and CTRL."
      Case 5
         Print "You pressed both SHIFT and ALT."
      Case 6
         Print "You pressed both CTRL and ALT."
      Case 7
         Print "You pressed SHIFT, CTRL, and ALT."
      End Select
End Sub

</Visual Baisc>

The third line in above code is:
ShiftTest = Shift And 7
The result of bit-wise comparison of Shift and 7 is stored in ShiftTest.

Why is this comparison necessary?
Can't we accomplish the same task without this comparison?

Thank you,

Syed Zeeshan Haider.
http://syedzeeshanhaider.faithweb.com/