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Microsoft KB Archive/171482

From BetaArchive Wiki

Article ID: 171482

Article Last Modified on 12/10/2003



APPLIES TO

  • Microsoft Visual Basic 5.0 Control Creation Edition
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition



This article was previously published under Q171482

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:

170365 : 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:

171554 : 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: kbbug kbfix kbvbp500sp2fix kbvs97sp2fix KB171482