PRB: License Collection vs. Standard Collection in For Each

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0

SYMPTOMS

The Licenses Collection handles the removal of elements differently from a standard VBA Collection object when you use it in a For Each loop. In a standard VBA Collection, if an item is removed during a For Each loop, the collection recognizes that the item is no longer an element and does not attempt to iterate over that element. In the Licenses collection, if an item is removed or the collection is cleared, the For...Each loop still iterates over that element of the collection. It does not recognize any changes made to the collection during the loop.

RESOLUTION

Do not attempt to access the members of the Licenses Collection in the same loop in which you are removing elements of the collection. Remove the unwanted licenses using the Clear or Remove methods before iterating over the collection in a For...Each loop. If you need to use a loop when removing elements, use two separate loops: one to remove the elements and one to access the remaining elements. See step 4 in the MORE INFORMATION section of this article for an example.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Start a new Standard EXE project is Visual Basic. Form1 is created by default.



2. Add the following code to the module of Form1.

   
         Private Sub Form_Load()
            Dim x As Variant
            Licenses.Add "RichText.RichTextCtrl"
            Licenses.Add "MSDBGrid.DBGrid"
            For Each x In Licenses
               Licenses.Clear
               MsgBox x
            Next
         End Sub 




3. Run the project. The message boxes display the elements of the collection even though they have been "cleared."



4. Stop the project and replace the code in step 2 with the following:

   
         Private Sub Form_Load()
           Dim x As Variant
           Licenses.Add "RichText.RichTextCtrl"
           Licenses.Add "MSDBGrid.DBGrid"
           Licenses.Clear
           For Each x In Licenses
              MsgBox x
           Next
         End Sub 




5. Run the project.

Additional query words:

Keywords : kbnokeyword kbVBp600 kbGrpVB
Version : WINDOWS:6.0;
Platform : WINDOWS
Issue type : kbprb