Q171835: FIX: Crash When Viewing Data Tips on ParamArray

Article: Q171835
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
========

A crash may occur while trying to display Data Tips in the IDE. This can occur
when you have a variant that contains an array of non-variants and pass the
element of that array to a ParamArray.

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. Start a new Standard EXE Project in Visual Basic 5.0.

2. Click on Project | Add Module to add a basic module to the project. Note that
  if you have Visual Basic 5.0 set up to automatically include "Option
  Explicit" to new modules, remove this line.

3. In the General Declarations area of the module, add the following code:

        Sub main()
            Dim x(5) as integer
            v = x
            r = Formt("????", v(5))
        End Sub

        Public Function Formt(str As String, ParamArray rgArgs()) As String
            Dim var As Variant
            Dim iPos As Integer, iLastPos As Integer
            Dim strRet As String

            iPos = 0
            iLastPos = 1
            For Each var In rgArgs
                iPos = InStr(iPos + 1, str, "?")
                If iPos < 1 Then Exit For
                strRet = strRet & Mid(str, iLastPos, iPos - iLastPos)
                strRet = strRet & var
                iLastPos = iPos + 1
            Next

            If Len(str) > iPos Then strRet = _
                          strRet & Right(str, Len(str) - (iPos))

            Formt = strRet
        End Function

4. From the Project menu select the Project1.Properties. On the General tab,
  make Sub Main the Startup Object.

5. Press the F5 key to run this program.

6. You will get a Type Mismatch error. Click on the dialog's Debug button.

7. In the following line of code:

        strRet = strRet & Mid(str, iLastPos, iPos - iLastPos)

  move the mouse pointer over the variable str to display the Data Tips. Once
  the Data Tip for this variable has been displayed, move to the next variable,
  iLastPos, to display its Data Tip. Go back and forth between the two
  variables several times.

8. Go to the following line of code:

         Public Function Format(str As String, ParamArray rgArgs()) _
                 As String

  and move the mouse pointer over rgArgs. At this point an Invalid Page Fault
  and an application error in Visual Basic is displayed.

Additional query words:

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