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Q171482: FIX: Crash When Enum Name Referenced Incorrectly

Article: Q171482
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0
Operating System(s): 
Keyword(s): kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- 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 incorrectly referring to an Enum name of a UserControl, such as treating
the Enum name as a Property of the UserControl, Visual Basic will give a fatal
error and close.

The error received will be similar to one of the following;

  VB5 caused an invalid page fault in module VB5.Exe...

  - or -

  The instruction at "0x004762d3 referenced memory at "0x0000000".
  The memory could not be "read"...

CAUSE
=====

The fatal error is the end result of incorrectly referencing a Enum name within
a UserControl. For example, if the following Enum is declared in the General
Declarations of a UserControl:

        Public Enum Salsa
           Mild
           Medium
           Hot
        End Enum

then an instance of UserControl is added to a form, and the Salsa enumeration is
referred to as:

        UserControl1.Salsa

The fatal error described above will occur. Enumerations behave like public
constants and cannot be referenced like a variable or property. To reference the
Salsa enumeration correctly, the user should reference Salsa.<membername>,
such as:

     Salsa.Hot

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been fixed in Visual Studio 97 Service
Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the
following article in the Microsoft Knowledge Base:

  Q170365 : INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97
Service Pack 2, please see the following article in the Microsoft Knowledge
Base:

  Q171554 : INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new Standard Exe project in Visual Basic 5.0. Form1 is created by
  default.

2. From the Project menu, select Add UserControl to add a UserControl
  (UserControl1) to the Project.

3. Add the following enumeration to the General Declarations section of the
  UserControl:

        Public Enum Salsa
                 Mild
                 Medium
                 Hot
              End Enum

4. Close both the UserControl1 code Window and the UserControl1 design Window.

5. Place an instance of the UserControl1 (UserControl11) onto Form1.

6. Add a CommandButton to Form1.

7. In the Click event of the CommandButton, add the following code:

        Usercontrol11.Salsa

8. Save and run the Project. Click the CommandButton to reproduce the problem in
  Visual Basic 5.0.

NOTE: This can also be reproduced simply by typing in the "UserControl11.Salsa"
line in the Click event. After typing the line, press the spacebar and note that
you get the same result.

Additional query words: kbDSupport

======================================================================
Keywords          : kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVBA500 kbVB500 kbZNotKeyword3
Version           : 5.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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