Q183164: FIX: For..Each Loop in ActiveX Component Causes Errors
Article: Q183164
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0
Operating System(s):
Keyword(s): kberrmsg kbVBp500 kbVBp500bug kbVBp600fix kbVS97sp2bug kbVS97sp3bug kbGrpDSVB
Last Modified: 06-MAR-2002
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The information in this article applies to:
- Microsoft Visual Basic Learning Edition for Windows, version 5.0
- Microsoft Visual Basic Professional Edition for Windows, version 5.0
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0
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SYMPTOMS
========
When using an ActiveX DLL created in Visual Basic, you may receive one of the
following errors if the ActiveX component contains a For..Each loop that
iterates through a Visual Basic collection:
Run-time error '48':
Error in loading DLL
-or-
Run-time error '-2147319765 (8002802b)':
Automation Error
This problem occurs when a For..Each loop is executed in an ActiveX DLL.
For..Each loops elsewhere do not exhibit this problem.
CAUSE
=====
This problem typically occurs after calling the DLL at least twice. The first
call into the DLL does not execute code that uses a For..Each loop but the
second call does. The error occurs during the second call. See the "Steps to
Reproduce Behavior" section below for more information.
RESOLUTION
==========
- Use a For..Next loop in place of the For..Each loop.
-or-
- Create your own collection class, an example of which can be found in the
Visual Basic Books Online. Refer to the topic "Creating Your Own Collection
Classes."
-or-
- If your DLL is running in a multithreaded environment like Internet
Information Server (IIS) or Microsoft Transaction Server (MTS), please see
the following article here in the Microsoft Knowledge Base:
Q186273 BUG: AV Running VB-Built Component in Multi-Threaded Environment
STATUS
======
Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article. This problem has been corrected in
Microsoft Visual Basic 6.0.
NOTE: If your DLL is running in a multi-threaded environment, you must still
complete the steps provided in the following article in the Microsoft Knowledge
Base:
Q186273 BUG: AV Running VB-Built Component in Multi-Threaded Environment
MORE INFORMATION
================
Steps to Reproduce Behavior
---------------------------
1. Create a new ActiveX DLL project in Visual Basic.
2. Click Project1 Properties from the Project menu and set the Project Name to
"AutoErr1."
3. Copy the following code to the Class1 module:
Public Sub Method1()
Dim col As New Collection
Dim obj As Object
For Each obj In col
Next obj
End Sub
4. Click "Make AutoErr1.dll" from the File menu to create the DLL file.
5. Quit Visual Basic. You may optionally save the project files.
6. Start Microsoft Excel 97 and create a new workbook. Press the ALT+F11 keys to
start the Visual Basic editor.
7. Click Module from the Insert menu to add a standard module. Add the following
code to the new module:
Private Sub Test48()
' First call into dll
Dim o as Object
Set o = CreateObject("AutoErr1.Class1")
Set o = Nothing
' Second call into dll
Set o = CreateObject("AutoErr1.Class1")
o.Method1 ' calls method that uses For..Each loop
set o = Nothing
End Sub
8. Press the F8 key to step through the Sub's code and note that the following
error occurs when calling Method1:
Run-time error '48':
Error in loading DLL
The following steps demonstrate how to reproduce the Automation error using
Visual Basic as the client. Note that these steps may not reproduce the error on
some machines.
1. Follow steps 1 through 5 above to create the AutoErr1.dll.
2. Start a new Standard EXE project in Visual Basic. Form1 is created by
default.
3. Place 2 CommandButtons (Command1 and Command2) on Form1.
4. Copy the following code to the Form1 module:
Private Sub Command1_Click()
' First call into dll
Dim o As Object
Set o = CreateObject("AutoErr1.Class1")
Set o = Nothing
End Sub
Private Sub Command2_Click()
' Second call into dll
Dim o As Object
Set o = CreateObject("AutoErr1.Class1")
o.Method1
Set o = Nothing
End Sub
5. Press the CTRL+F5 keys to run the project.
6. Click Command1.
7. Click Command2. Note that the following error may occur when calling
Method1:
Runtime-error '-2147319765 (8002802b)':
Automation Error
REFERENCES
==========
For additional information, please see the following article in the Microsoft
Knowledge Base:
Q178777 : PRB: ASP Returns "Error in Loading DLL" with VB Component
Additional query words: element not found
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Keywords : kberrmsg kbVBp500 kbVBp500bug kbVBp600fix kbVS97sp2bug kbVS97sp3bug kbGrpDSVB
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB500
Version : :5.0
Issue type : kbbug
Solution Type : kbfix
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