FIX: ALEN() Function Causes Illegal Operation in Debug Window (162553)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 3.0
  • Microsoft Visual FoxPro for Windows 3.0b
This article was previously published under Q162553

SYMPTOMS

Using the ALEN() function in the Debug window to reference an array that does not exist in a form causes Visual FoxPro 3.0 for Windows to shut down. The following error message appears in Windows 95 after the form closes:
This program has performed an illegal operation and will be shut down.
Clicking Details reveals the following message:
VFP caused an invalid page fault in module <module name> at <memory address>.
In Windows NT 4.0, the following error appears:
An application error has occurred and an application error log is being generated.

VFP.exe
Exception: access violation <error number>, Address: <memory address>.
The operating system then closes Visual FoxPro.

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 FoxPro 5.0 for Windows.

MORE INFORMATION

Steps to Reproduce Behavior

  1. Create a form called ztest.scx.
  2. Add a command button to the form. In the Click event of the button, place the following code: 
          ThisForm.Release
  3. Save the form.
  4. Invoke the Debug window, type the following line, and press the Enter key:

    ALEN(ThisForm.atest)

    This references a nonexistent array.
  5. Run the form and click the command button to close the form.
  6. The error occurs and Visual FoxPro shuts down.
Modification Type:MajorLast Reviewed:9/30/2003
Keywords:kbBug kbfix kbvfp500fix KB162553
©2003 Microsoft Corporation. All rights reserved.