[RESOLVED] Error on setting checkstate in a CheckedListBox control

I have a CheckedListBox control that I fill with DataGridView Column HeaderText values. If these columns are visible, I would like to set the CheckedListBox Items to "Checked". My code is as follows:

Code:

---

For Each col As DataGridViewColumn In frmTimingP2P.dgvOverview.Columns
    If col.Visible = True Then
        For Each item In clbOverviewColumnOrder.Items
            Dim intItemIndex As Integer = clbOverviewColumnOrder.Items.IndexOf(item)
            If col.HeaderText = item.ToString Then
                clbOverviewColumnOrder.SetItemCheckState(intItemIndex, CheckState.Checked)
            End If
        Next
    End If
Next

---

Whenever this code runs, I get the following error:

"List that this enumerator is bound to has been modified. An enumerator can only be used if the list does not change."

What causes this? How can I get around this issue?

Thanks

In this case you cannot use a foreach loop, it's like trying to remove controls using a foreach loop. Instead you have to loop through the items using a for loop and looping them backwards. Take a look at this:

Code:

---

        Dim checked As Boolean = True 'or false
        For i As Integer = CheckedListBox1.Items.Count - 1 To 0 Step -1
            CheckedListBox1.SetItemChecked(i, checked)
        Next

---

looks like it doesnt want you to edit the control while your using the enumerator(thing keeping track of the ForEach/Next loop)

try For/Next loop instead

Got it. I revised my code and ended up with the following:

Code:

---

Dim intCurrentItemIndex As Integer = clbOverviewColumnOrder.Items.Count - 1
        Do While intCurrentItemIndex >= 0
            Dim strCurrentItem As String = clbOverviewColumnOrder.Items(intCurrentItemIndex)
            For Each col As DataGridViewColumn In frmTimingP2P.dgvOverview.Columns
                If col.HeaderText = strCurrentItem Then
                    If col.Visible = True Then
                        clbOverviewColumnOrder.SetItemCheckState(intCurrentItemIndex, CheckState.Checked)
                    Else
                        clbOverviewColumnOrder.SetItemCheckState(intCurrentItemIndex, CheckState.Unchecked)
                    End If
                End If
            Next
            intCurrentItemIndex -= 1
        Loop

---

It works perfectly. Thanks!

If I could make a suggestion, don't use a do while in this situation. While it may work, it's quicker to use the for loop I showed above. Pretty much anytime you can use a for loop rather than a do loop, then choose the for loop.

That is interesting. I was unaware that a For...Next loop was any quicker than a Do...Loop.