Re: Usisng logical operators with integers in VB

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"Bill McCarthy" <Bill@xxxxxxxxxx> wrote in message news:OJEjoQbqIHA.524@xxxxxxxxxxxxxxxxxxxxxxx
Hi Werden,

The And operator and Or operators are bitwise. As well there's the Xor and Not operators. But as to a greater than operator that is bitwise, I actually have never heard of such a thing.

So that if A = 3 and B = 9 then result would be 2.

I don't get this. 3 would be in bits 0011, while 9 would be 1001, so how would you get 2 ?

Maybe A Xor (A And B) ?




okay. Using Tom's options enum

Option1 = &H1
Option2 = &H2
Option3 = &H4
Option4 = &H8

Say I had Option1 (&H1) and Option2 (&H2) set to true for a record (A) in a table, the integer would be stored as 3. Now I add a new record (B) and it has Option1 and Option4 (&H8) set to true so it's stored as 9. *But* although I want to store multiple settings, I don't want have duplicate settings across these records, so I need to remove the Option 1 from the record A.

A B = New A Value
0 1 = 0
0 0 = 0
1 0 = 1
1 1 = 0

So that A now equals 0010 or 2, B is still 1001 or 9 and now don't have any duplicate options set.


I ended up just making a function to do it like this..

Shared Function logical_A_GreaterThan_B(ByVal A As Integer, ByVal B As Integer) As Integer

Dim i As Integer
Dim n As Integer

For i = 0 To 30 ' 2^31 overflows an integer by 1 so let's just do the first 30 bits

n = CInt(2 ^ i)

If CBool(A And n) Then 'if bit in A is 'on'
If CBool(B And n) Then 'if bit in B is 'on'
A -= n 'Turn bit in A 'off'
End If
End If

Next

Return A

End Function


.

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