Empty values return by random funciton

[Cainnech]

Hi guys,

I'm completely stupified by this silly randomizer function.

It's often returning me empty values and I have no idea why.

I want to generate random number between 0 and 5 but I want to prevent that the same number is being generated twice in a row.

Here's the code

Dim LastNumber as Integer
 
Private Sub Form_Load()
    Randomize
    LastNumber = 99
    Tmr_Timer.enabled = true    
End Sub
 
Private Sub Tmr_Timer()
    MsgBox (Random)
End Sub
 
Public Function Random()
    Dim RNumber As Integer
 
    RNumber = Int(Rnd(1) * 5) + 0
 
 
    If RNumber <> LastNumber And RNumber <> vbNull Then
 
        LastNumber = RNumber
        Random = RNumber
    End If
 
End Function
 

Anybody has an idea why this doesn't work?

Thanks,
Kenneth

[Rabbit]

It's because when the number repeats, you never generate another number. Also, you're not going to get the range 0-5, you'll only get 0-4.

[Cainnech]

Thanks Rabbit for your response, but what would be the solution then? Because I can't just call Random again...

[Rabbit]

Yes you can. That's exactly the solution. Call random until you get a non-repeating number.

[Cainnech]

Well I think there's another problem then because I added the Random to the code but I still get empty values.

Public Function Random()
    Dim RNumber As Integer
 
    RNumber = Int(Rnd(1) * 6) + 0
 
    If RNumber <> LastNumber And RNumber <> vbNull Then
 
        LastNumber = RNumber
        Random = RNumber
 
    Else
 
        Random
 
    End If
 
End Function
 

[Rabbit]

That's because the first random call is still the function that will get returned to the timer and you haven't assigned it the value of the next random call.

[Cainnech]

And how can I assign the value of the next random call then?

[Rabbit]

Random = Random()

[Cainnech]

Yes that did it.
It's a bit confusing since in VB6 you normally call a function just by using the Functionname without the brackets.

So when I was calling Random in the else statement, I thought I was actually calling the function again.

But now it's making a bit more sense.

Thanks Rabbit!

[Killer42]

If you have a look in the Insights section for VB 4/5/6, there's an article on generating non-repeating random numbers. It includes a self-contained function to generate them for you.

Also, take care when writing recursive code, it can easily get out of control. (That is, code which calls itself like your Random function here). It's easy to get stuck in a loop and fill up the stack.