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Q297839: FIX: TYPE() of Combo/List Box Value May Crash VFP

Article: Q297839
Product(s): Microsoft FoxPro
Version(s): 3.0,3.0b,5.0,5.0a,6.0
Operating System(s): 
Keyword(s): kbvfp kbvfp300 kbvfp300b kbvfp500aBUG kbvfp500bug kbvfp600bug kbGrpDSFox kbDSupport
Last Modified: 15-SEP-2001

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0 
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SYMPTOMS
========

In Visual FoxPro version 5.0 and later, if the RowSource of a list box or combo
box is a non-existent table and you check the TYPE() of the Value property
during the form's Init method, you may receive the following error message:

  Fatal error: Exception code=C0000005

In Visual FoxPro version 5.0a, you may receive the following error message:

  Internal Consistency error.

STATUS
======

This problem was corrected in Microsoft Visual FoxPro version 7.0 for Windows.

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

This behavior does not occur in Visual FoxPro version 3.0. An error occurs, and
the form does not appear.

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

The following code creates and runs a form that demonstrates the problem.

  SET SAFETY OFF
  CLEAR ALL
  CLOSE DATABASES ALL

  CREATE FORM testType NOWAIT
  ASELOBJ(laObj, 1) && Gives you the form containing the selected object.

  loForm = laObj[1]
  loForm.AutoCenter = .T.

  loForm.AddObject('lstValues','listbox')
  WITH loForm.lstValues
     .RowSourceType = 6
     .RowSource = "testTable.f1"
     .Name = "lstValues"
  ENDWITH

  loForm.WriteMethod('Init', [WAIT WINDOW TYPE("ThisForm.lstValues.Value")])

  KEYBOARD 'Y' CLEAR  && Answers "Yes" to Save dialog.
  RELEASE WINDOW 'Form Designer'

  DO FORM testType

Additional query words:

======================================================================
Keywords          : kbvfp kbvfp300 kbvfp300b kbvfp500aBUG kbvfp500bug kbvfp600bug kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a
Version           : :3.0,3.0b,5.0,5.0a,6.0
Issue type        : kbbug
Solution Type     : kbfix

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