indirect name referencing in vb.net

Question

my code goes like
for each c as control in controls
if c.name = "chklst" + counter then
c.items.add(newitem)
end if
next
the problem im having is "c.items.add(newitem)" doesnt work, if i replace "c" with the direct name it works but as it is it doesnt. how can i properly add an item in this case?
or perhaps theres a better way for me to indirectly reference the name?

Answer 1

Hi

Here is a hacked up version that works. Hacked up because I had to invent some details for the example.

    ' in your case the listbox is already
    ' on the Form
    Dim chklst As New CheckedListBox
    chklst.Name = "chklst123"
    Controls.Add(chklst)

    ' I have invented newitem value
    Dim newitem As String = "123456789"

    Dim counter As String = "123"
    For Each c As Control In Controls
      If c.Name = "chklst" + counter Then
        Dim cont As CheckedListBox = TryCast(c, CheckedListBox)
        If Not cont Is Nothing Then cont.Items.Add(newitem)
      End If
    Next

Answer 2

Maybe you must cast c to the type of your control. For example, if it is CheckedListBox:

Dim lb = CType(c, CheckedListBox)
lb.Items.Add(newitem)

Or show more details about "doesnt work".

Answer 3

In C#, a foreach loop iterate over all the elements in a collection. During each pass through the loop, the loop variable is set to an element from the collection. But the loop variable is readonly, so any changes you apply will be discarded.

So basically, if you want to add a control, you need to create a new variable that points to the control and then use add child controls. Refer:

https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.control.findcontrol?view=netframework-4.8