Getting the text of all check boxes in a tabcontrol to a string - tabcontrol

Question

I am extremely new to all of this, and whilst I have tried searching I cant find anything that has helped me achieve what I am after.
I have a form in VB with the following:
1 x tabcontrol
10 x checkboxes which sit in various tabs on the tab control
1 x listbox
When i tick any of the check boxes, I want their text to be added to the listbox, and when I untick, their text to be taken from the listbox.
I can achieve this very easily using if statements for the changedcheck event for each checkbox but I have to do that for every single checkbox which isn't very efficient as potentially i could have 20,30 40+ check boxes. Plus if I add one at a later stage I would have to remember to add its code.
Ideally i want a method that's says: check all the checkboxes in tabcontrol if there value is true write their text to a string, if there value is false, take there text from the string. put the string in the listbox.
I started with something like this...
Dim chk As CheckBox
Dim txt As String = ""
For Each chk In TabControl1.Controls
If chk.Checked = True Then
txt = txt + chk.Text +vbCrLF
Else
txt = replace(txt, chk.text + vbCrLf, "")
End If
Next
End Sub
First problem is that the above obviously doesn't work! so any guidance there is appreciated - i put it together from reading scraps from other code.
Second problem is, i can't get my head round how the list box will be updated, as previously i was using the CheckedChanged event for each control, which if i do what i want, then there wont be a specific CheckedChanged event, as it could be any of the checkboxes (hopefully that makes sense!). I don't want to have to press a button to add the checked checkboxes to the listbox, i want it to be dynamic
any help is very much appreciated.

Answer 1

For your first problem add
Dim chk As Control
Dim txt As String = ""
For Each chk In TabControl1.Controls
If TypeOf chk Is CheckBox
If DirectCast(chk, CheckBox).Checked = True Then
txt = txt + chk.Text +vbCrLF
Else
txt = replace(txt, chk.text + vbCrLf, "")
End If
End If
Next
End Sub
For your second problem in CheckedChanged event you can do something like this:
Private Sub OnCheckedChanged(sender as Object, e as EventArgs) _
Handles CheckBox1.CheckedChanged
Dim chk As CheckBox = TryCast(s, CheckBox)
Dim txt as string
If c.Checked = True Then
txt = chk.Text
EndIf
End Sub