VB .NET Strange Behaviour When Removing Form Controls

[sgeklor]

Hi guys,

I have a panel on a form and at runtime I create some controls on the panel. Then, also during runtime I want to clear the panel of all of its controls. The basic way to do this is with the following code:

For Each this_ctrl As Object In target_panel.Controls
     this_ctrl.Dispose()
Next

What happens when I use this code is that only every second control is removed from the panel! Yet, when I replace the .Dispose() method with some other behaviour (like change the control's colour) it appears that every control is accessed correctly. Repeating the code block iteratively removes every second control until none are left, but this is hardly an elegant way to proceed.

So I think this is strange. Can anyone suggest a cause for the problem, or another way of clearing the panel?

Thanks heaps,

Ash

PS: I'm using Visual Studio 2005

[jigsmshah]

Hi guys,

I have a panel on a form and at runtime I create some controls on the panel. Then, also during runtime I want to clear the panel of all of its controls. The basic way to do this is with the following code:

For Each this_ctrl As Object In target_panel.Controls
     this_ctrl.Dispose()
Next

What happens when I use this code is that only every second control is removed from the panel! Yet, when I replace the .Dispose() method with some other behaviour (like change the control's colour) it appears that every control is accessed correctly. Repeating the code block iteratively removes every second control until none are left, but this is hardly an elegant way to proceed.

So I think this is strange. Can anyone suggest a cause for the problem, or another way of clearing the panel?

Thanks heaps,

Ash

PS: I'm using Visual Studio 2005

See it is not strange,you iterating the Collection object and remove the controls
from it so the for loop wont iterate for the number of controls you have in the panel.Instead of Dispose you try to make controls invisible,the for loop will work properly as you are not deleting the controls from the ControlCollection.
Hope it makes sense.

try to use
panel.Controls.Clear();

Regards
Jignesh

[sgeklor]

Brilliant!!! The .Clear() method works perfectly.

In general though, I didn't realise the limitations of "For Eaching" through an ArrayList.

What if I had a general ArrayList and wanted to remove some elements from it (those that match some criteria) by "For Eaching" through the list. Then by disposing those members that I do not want will I not have the same problem?

What is the correct way to iterate through and remove some members from an ArrayList?

Thanks,

Ash