Power of 2...

[r0ach]

I feel stupid asking this question, and i'll probably kick myself if i see the solution. I need to determine whether a number is a power of two (2, 4, 8, 16, 32, etc.). Can someone please help.

[kedaman]

Use this example of logaritmics:

if Log(value) / Log(2) = int(Log(value) / Log(2))then
 msgbox value & "is 2^" & Log(value) / Log(2) 
end if

[Edited by kedaman on 05-30-2000 at 02:23 PM]

[Mark Sreeves]

may as well post it even though kedaman beat me to it!

Option Explicit

Private Sub Command1_Click()
Dim retval As Double

retval = Log2(Val(Text1))

If retval = Int(retval) Then
  MsgBox "number is a power of 2"
Else
  MsgBox "number is not a power of 2"
End If

End Sub
Static Function Log2(X)
  Log2 = Log(X) / Log(2#)
End Function

[r0ach]

I feel stupid. Thanx guys.
I thought of Log and checking if value = Int(Value).

I just didn't know how to put it all together.

Never could understand this Log stuph.

[kedaman]

You're right about that, i don't like your function. ok i'm making a isbase2 one here:

Function isbase2(value) as boolean
 isbase2 = Log(value) / Log(2) = int(Log(value) / Log(2))
End Function