以编程方式删除控件未按预期工作

Question

I have 11 panels in each tabpage of a tabcontrol and want to remove 10 panels. so I wrote this code:

        var PnlsToRemove = tabControl.SelectedTab.Controls.OfType<Panel>()
            .Where(p => !p.Name.StartsWith("BasePanel"));
        foreach (var pnl in PnlsToRemove)
            pnl.Dispose();

but after tracing I wondered that remove order is alternate!
means that when above code runs just panels 0,2,4,6,8,10 will remove and the others remains.
so I should put my code in a loop to remove panels alternately like this:

    while (tabControl.SelectedTab.Controls.OfType<Panel>().Count() != 1)
    {
        var PnlsToRemove = tabControl.SelectedTab.Controls.OfType<Panel>()
            .Where(p => !p.Name.StartsWith("BasePanel"));
        foreach (var pnl in PnlsToRemove)
            pnl.Dispose();
    }

in this case(for 10 panels) while() loops 4 times to remove all the panels.

NOTICE: all of my panels exist in "PnlsToRemove" and this bug occurs on execution of "PnlsToRemove" in foreach.

So, what's wrong with my code?
Why foreach() jumps from next panel?

I think every thing is clear!

Answer 1

The underlying collection is being mutated as you remove the panels from the list, and this is apparently being reflected in the values seen by the "foreach". The solution is to store the values into a new collection and iterate over that. You should be able to do this by adding a ".ToList()" to your definition of PnlsToRemove