BUG: Removing Collection Elements Takes Longer Than Expected

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

SYMPTOMS

In Visual Basic 6.0, removing elements from the end of a collection takes longer than removing elements from the beginning.

CAUSE

When removing an element from a collection, Visual Basic 6.0 begins at the beginning of the collection and traverses the collection until the desired element is reached, then that element is removed.

RESOLUTION

Remove elements from the beginning of the collection rather than the end.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Behavior

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



2. Select Add Module from the Project menu. This will create Module1.



3. Select Project1 Properties from the Project menu. Change the Startup Object to Sub Main.



4. Copy and paste the following code into Module1:

   
         Sub Main()
   
            Dim c As New Collection
            Dim a As Long
   
            Set c = New Collection
   
            'Add elements to collection
            For a = 1 To 10000
               c.Add "Thank you sir, may I have another."
            Next a
            MsgBox "Done adding elements"
   
            'Remove elements from end, this takes long time
            For a = 10000 To 1 Step -1
               c.Remove a
            Next a
            MsgBox "Done removing elements from end"
   
            'Add elements to collection again
            For a = 1 To 10000
               c.Add "Thank you sir, may I have another."
            Next a
            MsgBox "Done adding elements"
   
            'Remove elements from beginning, this is much quicker
            For a = 1 To 10000
               c.Remove 1
            Next a
            MsgBox "Done removing elements from end"
          End Sub 




5. Press the F5 key to run the project. Note the time difference between the two methods of deleting elements from a collection.

Additional query words: kbDSupport kbVBp600bug kbVBp kbdss kbNoKeyWord

Keywords : kbGrpVB
Version :
Platform : WINDOWS
Issue type : kbbug