[RESOLVED] randomly selecting number then excluding it

[AC_AC_AC187]

am making a multiple-choice question game and want the user to select either a 10 or 20 question game. i should be fine with that much of it, but what i need help with is randomly selecting a number between 1 and 25 (will only choose 10 or 20 of the 25 questions) and then excluding that randomly selected number from being randomly selected again so that question won't be chosen again in the same game...

[AC_AC_AC187]

i was thinking i could have an array containing the numbers 1 to 25 and randomly selecting one of those numbers and loading the question, then setting that chosen number to 0. (and make it so that when randomly selecting a number from the array it has to be greater than 0 and if it's not randomly select another number)

[FES Germany]

yes, have another array bolChoosen(1 to 25)
get intRandom

do
x = intRandom
loop until bolchoosen(x) = false

[Logophobic]

Easiest would be to create an array containing the numbers, shuffle the array so that the numbers are in some random order, then take the first 10 or 20 numbers from the array.

[AC_AC_AC187]

that's a decent idea, how hard is it to shuffle the integers in the array?
(i don't want to randomly generate a number for each cell because i want every number from 1 to 25 to occur once)

[Ellis Dee]

This will shuffle any native-type array: (Strings, Longs, etc... Not UDT arrays, sadly.)

' Knuth shuffle (very fast)
Public Sub ShuffleArray(pvarArray As Variant)
    Dim i As Long
    Dim iMin As Long
    Dim iMax As Long
    Dim lngReplace As Long
    Dim varSwap As Variant
    
    iMin = LBound(pvarArray)
    iMax = UBound(pvarArray)
    For i = iMax To iMin + 1 Step -1
        lngReplace = Int((i - iMin + 1) * Rnd + iMin)
        varSwap = pvarArray(i)
        pvarArray(i) = pvarArray(lngReplace)
        pvarArray(lngReplace) = varSwap
    Next
End Sub

Sample usage:

Public Sub Sample()
    Dim lngArray(1 To 25) As Long
    Dim i As Long
    
    For i = LBound(lngArray) To UBound(lngArray)
        lngArray(i) = i
    Next
    ShuffleArray lngArray
    ' Pick 20 random numbers
    For i = 1 To 20
        Debug.Print lngArray(i)
    Next
End Sub

[Ellis Dee]

Note that because shuffling uses random numbers, you should include a Randomize statement in Sub Main() or your startup form's Form_Load().

[AC_AC_AC187]

thanks heaps for that!

like this? (listbox is just to view result)...

then how would i load each question (form) in that shuffled order? (show next form after user submits answer on previous form)

[MartinLiss]

Assuming that you forms are named Form1, Form2, Form3, etc...

    Dim frm As Form
    Set frm = Forms.Add("Form" & lstbox.Text)
    frm.Show

But why do you need one form per question?

[AC_AC_AC187]

it's a project for school and that's the way it's gotta be done...

[AC_AC_AC187]

is it possible to use form names instead of the numbers? (such as frmMain)
and is it possible to load a form from its name in the array?
so that i could do something like this...??

question = 'random form name from shuffled array
me.hide
question.show

[MartinLiss]

This should work but I haven't tested it.

Option Explicit

Private Type frm_names
    Form_Name As String
    Form_Nbr As Integer
End Type
Private Form_Names(1 To 25) As frm_names
    
Public Sub ShuffleArray(pvarArray As Variant)
    Dim i As Long
    Dim iMin As Long
    Dim iMax As Long
    Dim lngReplace As Long
    Dim varSwap As Variant
    
    iMin = LBound(pvarArray)
    iMax = UBound(pvarArray)
    For i = iMax To iMin + 1 Step -1
        lngReplace = Int((i - iMin + 1) * Rnd + iMin)
        varSwap = pvarArray(i)
        pvarArray(i) = pvarArray(lngReplace)
        pvarArray(lngReplace) = varSwap
    Next
End Sub

Public Sub cmdbtn_Click()
Dim lngArray(1 To 25) As Long
Dim i As Long

lstbox.Clear

For i = LBound(lngArray) To UBound(lngArray)
lngArray(i) = i
Next
ShuffleArray lngArray
For i = 1 To 20
lstbox.AddItem lngArray(i)
Next
End Sub

Private Sub Form_Load()
    'Load frm_Names
    Form_Names(1).Form_Name = "frmOne"
    Form_Names(1).Form_Nbr = 1
    Form_Names(1).Form_Name = "frmTwo"
    Form_Names(1).Form_Nbr = 2
    Form_Names(1).Form_Name = "frmBlah"
    Form_Names(1).Form_Nbr = 3
    'etc
    End Sub

Private Sub lstbox_Click()

    Dim lngIndex As Long
    Dim frm As Form
    
    For lngIndex = 1 To 25
        If Form_Names(lngIndex).Form_Nbr = lstbox.Text Then
            Set frm = Forms.Add(Form_Names(lngIndex).Form_Name)
            Exit For
        End If
    Next
    frm.Show
    
End Sub

[AC_AC_AC187]

ok, modified the code and am getting a type mismatch run-time error... not sure if i implemented the code correctly?

please help asap, this is due tomorrow afternoon.

[AC_AC_AC187]

started a new project again, just copying the code from your last post. this time getting a variable not set run-time error

struggling...

[AC_AC_AC187]

just figured out that the type mismatch error was from not selecting an item in the listbox before clicking the command button. then it gives me the same variable not set run-time error aswell...

[MartinLiss]

just figured out that the type mismatch error was from not selecting an item in the listbox before clicking the command button. then it gives me the same variable not set run-time error aswell...

Do you need advice on how to stop the error from happening?

[AC_AC_AC187]

yes please, i really need to get this working before tomorrow if possible...

[leinad31]

In the command button click event check if Listbox.ListIndex = -1, if it is then theres no item selected so branch processing accordingly or Exit Sub.