FIX: Crash When Viewing Data Tips on ParamArray

• Microsoft Visual Basic Control Creation, Learning, Professional, and Enterprise Editions for Windows, version 5.0

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

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 kbGrpVB kbvbp500sp2fix
Version : 5.0
Platform : WINDOWS
Issue type : kbbug