ArrayList problem

[leazfe]

I have used an arrayList in order to avoid te capacity problems. But, i am getting the next error when i try to iterate over all elements:

An unhandled exception of type 'System.InvalidOperationException' occurred in mscorlib.dll
Additional information: Collection was modified; enumeration operation may not execute.

The code is:

For Each tmpTree In ar
    If tmpTree.IsLeaf Then
       ar.Remove(tmpTree)
    End If
Next

The Message is enought clear, but really am I not able to modifie the arraylist?

Thanks,
Álvaro

[pax]

Hi.

You can't use "For Each" on a collection, if you are going to remove items in that very collection.
Simply because, it has no idea where to go next, cuz' you just removed it's reference.

What you need to do is this :

For I= ar.Length-1 To 0 Step -1
    tmpTree=ar(I)
    If tmpTree.IsLeaf Then
       ar.RemoveAt(I)
    End If
Next

This will run through the collection backwards, removing as it goes. But because it's running backwards, and using an indexpointer, it still knows where to go next.

Hope this clears things up a bit.