code multiple comboboxes on excel userform - excel

Question

I have a userform with multiple dependent Comboboxes. I would like to add the following code to 10 of the Comboboxes Change event. The Comboboxes to be coded are Numbered 11 to 20 (Combobox11, Combobox 12, etc) while the dependent Comboboxes are numbered 21 to 30.
I could copy and paste the code 10 times and then find and replace the relevant Combobox Nos.
Is there a way to use a loop through the Combo-Boxes to achieve this?
Any assistance would be most grateful.
Private Sub ComboBox11_Change()
Dim index As Integer
index = ComboBox11.ListIndex
ComboBox21.Clear
Select Case index
Case Is = 0
With ComboBox21
.RowSource = Range("SubCat1").Address(external:=True)
End With
Case Is = 1
With ComboBox21
.RowSource = Range("SubCat6").Address(external:=True)
End With
Case Is = 2
With ComboBox21
.RowSource = Range("SubCat7").Address(external:=True)
End With
Case Is = 3
With ComboBox21
.RowSource = Range("SubCat8").Address(external:=True)
End With
Case Is = 4
With ComboBox21
.RowSource = Range("SubCat9").Address(external:=True)
End With
'and several more case options
End Select
End Sub

Answer 1

You can use a Class Module, and a User_Init Sub to set each ComboBox control in the user form to this class.
In my code I used Main_Form as the name of the User_Form, modify the code according to your User_Form Name.
Add a Calls Module, and add this code below in Class 1:
Public WithEvents ComboBoxEvents As MSForms.ComboBox
' anytime a Change event occurs to any ComboBox, the Sub is triggered
Private Sub ComboBoxEvents_Change()
Dim ComboBox_Index As String
Dim index As Integer
With ComboBoxEvents
' read the index of the ComboBox, as long as the names remain ComboBox1, ComboBox2, ComboBox3, etc...
ComboBox_Index = Mid(.Name, 9)
' run this code if it's ComboBox 11 to 20
If ComboBox_Index >= 11 And ComboBox_Index <= 20 Then
index = .ListIndex
Select Case index
Case Is = 0
With Main_Form.Controls("ComboBox" & ComboBox_Index + 10)
.RowSource = Range("SubCat1").Address(external:=True)
End With
Case Is = 1
With Main_Form.Controls("ComboBox" & ComboBox_Index + 10)
.RowSource = Range("SubCat6").Address(external:=True)
End With
Case Is = 2
With Main_Form.Controls("ComboBox" & ComboBox_Index + 10)
.RowSource = Range("SubCat7").Address(external:=True)
End With
Case Is = 3
With Main_Form.Controls("ComboBox" & ComboBox_Index + 10)
.RowSource = Range("SubCat8").Address(external:=True)
End With
Case Is = 4
With Main_Form.Controls("ComboBox" & ComboBox_Index + 10)
.RowSource = Range("SubCat9").Address(external:=True)
End With
'and several more case options
End Select
End If
End With
End Sub
The code below goes in your User_Form_Init (in my code the name of the User_Form is Main-Form) :
Option Explicit
Dim ComboBoxes() As New Class1
Private Sub UserForm_Initialize()
Dim ComboBoxCounter As Integer, Obj As Control
For Each Obj In Me.Controls
If TypeOf Obj Is MSForms.ComboBox Then
ComboBoxCounter = ComboBoxCounter + 1
ReDim Preserve ComboBoxes(1 To ComboBoxCounter)
Set ComboBoxes(ComboBoxCounter).ComboBoxEvents = Obj
End If
Next Obj
Set Obj = Nothing
End Sub

Answer 2

the way is using Class
add a Class module and name it after "CmbBox" (you can choose whatever name but be consistent with it)
add the following code into the class code pane:
Option Explicit
Public WithEvents Cmb As MSForms.ComboBox
Private Sub Cmb_Change()
Dim index As Long
With Cmb
index = .ListIndex
With .Parent.Controls("ComboBox" & Mid(.Name, 9) + 10)
.Clear
Select Case index
Case 0
.RowSource = Range("SubCat1").Address(external:=True)
Case 1 To 4
.RowSource = Range("SubCat" & index + 5).Address(external:=True)
End Select
End With
End With
End Sub
Then switch to your userfom code pane and add this code:
Dim Cmbs(1 To 10) As New CmbBox '<--| this must be at the very top of your userform code pane
Sub Userform_Initialize()
Dim i As Long
With Me.Controls
For i = 11 To 20
Set Cmbs(i - 10).Cmb = .Item("ComboBox" & i)
Next i
End With
End Sub
and that's it