KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q158755: FIX: CLEAR ALL with Object References Causes Page Fault

Article: Q158755
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0
Operating System(s): 
Keyword(s): kberrmsg
Last Modified: 24-MAR-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 5.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

If there are objects that reference each other, Visual FoxPro displays the
following error message when CLEAR ALL is carried out:

  This Program has performed an illegal operation and will be shut down.

Visual FoxPro terminates due to an Invalid Page Fault.

WORKAROUND
==========

Delete object references before carrying out CLEAR ALL.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products listed at
the beginning of this article. This has been corrected in Visual FoxPro 6.0.

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

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

1. Create and run a program containing the following code:

        oform = CreateObject( "Form" )
        oform.AddObject("X", "CB")
        oform.AddObject("Y", "CB")
        oform.y.pointer=oform.x
        oform.x.pointer=oform.y
        CLEAR ALL  && This causes an Invalid Page Fault and
                   && shuts down Visual FoxPro.

        DEFINE CLASS CB as CommandButton
          pointer= .NULL.
        ENDDEFINE

Object references for "X" and "Y" above can be cleared by doing the following:

        oform.removeobject("X")
        oform.removeobject("Y")

Additional query words: vfoxwin kbdsd kbvfp500 kbvfp600fix

======================================================================
Keywords          : kberrmsg 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500
Version           : WINDOWS:5.0
Issue type        : kbbug
Solution Type     : kbfix

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.