Q177271: WD97: Converted WordBasic On Error Statements May Fail

Article: Q177271
Product(s): Word 97 for Windows
Version(s): WINDOWS:97
Operating System(s): 
Keyword(s): kbcode kbProgramming kbmacroexample word8 kbwordvba word97
Last Modified: 13-MAY-2002

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The information in this article applies to:

- Microsoft Word 97 for Windows 
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SYMPTOMS
========

When you run a Microsoft Visual Basic for Applications procedure or macro that
was converted from a WordBasic procedure or macro that contained error trapping,
the error trap is ignored though it worked as expected when run in WordBasic.

CAUSE
=====

Microsoft provides programming examples for illustration only, without warranty
either expressed or implied, including, but not limited to, the implied
warranties of merchantability and/or fitness for a particular purpose. This
article assumes that you are familiar with the programming language being
demonstrated and the tools used to create and debug procedures. Microsoft
support professionals can help explain the functionality of a particular
procedure, but they will not modify these examples to provide added
functionality or construct procedures to meet your specific needs. If you have
limited programming experience, you may want to contact a Microsoft Certified
Partner or the Microsoft fee-based consulting line at (800) 936-5200. For more
information about Microsoft Certified Partners, please visit the following
Microsoft Web site:

  http://www.microsoft.com/partner/referral/

For more information about the support options that are available and about how
to contact Microsoft, visit the following Microsoft Web site:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

By design, the On Error statement in Visual Basic works differently from
WordBasic. In Visual Basic, On Error is not cleared when an error occurs, while
in WordBasic, the On Error statement is cleared, the error trap is reset, and
your code continues to run.

Therefore, the following sample converted WordBasic code fails when an error
occurs the second time.

     Sub Main()
        ' Clear error trap. Set error trap.
        On Error GoTo -1: On Error GoTo ErrorTrap
        ' Loop 10 times.
        For i = 1 To 10
           ' Artificially raise an error.
           Err.Raise 5
     ErrorTrap:
          ' Decision tree based on error returned.
          If Err.Number = 0 Then
              ' If no error occurred, do this...
              count_ = count_ + 1
          Else
              ' Else, if error occurred, do this...
              Err.Number = 0
          End If
        Next
     End Sub

RESOLUTION
==========

To resolve this issue, make the On Error statement the first statement inside
the loop.

     Sub Main()
        ' Loop 10 times.
        For i = 1 To 10
        ' Clear error trap. Set error trap.
        On Error GoTo -1: On Error GoTo ErrorTrap
           ' Artificially raise an error.
           Err.Raise 5
     ErrorTrap:
          ' Decision tree based on error returned.
          If Err.Number = 0 Then
              ' If no error occurred, do this...
              count_ = count_ + 1
          Else
              ' Else if error occurred, do this...
              Err.Number = 0
          End If
        Next
     End Sub

In this example, the Err.Raise statement artificially raises an error for
demonstration purposes. When the error occurs and the next iteration of the loop
occurs, the "On Error GoTo -1" statement clears the error trap and the "On Error
GoTo ErrorTrap" statement resets the error trap. The loop continues to process
without interruption until it completes the designated number of iterations
(10).

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products listed at
the beginning of this article.

REFERENCES
==========

For more information about the On Error Statement, click the Office Assistant in
the Visual Basic Editor, type "On Error" (without the quotation marks), click
Search, and then click to view "On Error Statement."

NOTE: If the Assistant is hidden, click the Office Assistant button on the
Standard toolbar. If Word Help is not installed on your computer, please see the
following article in the Microsoft Knowledge Base:

  Q120802 Office: How to Add/Remove a Single Office Program or Component

For more information about getting help with Visual Basic for Applications,
please see the following article in the Microsoft Knowledge Base:

  Q163435 VBA: Programming Resources for Visual Basic for Applications

Additional query words: wordcon vba

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Keywords          : kbcode kbProgramming kbmacroexample word8 kbwordvba word97 
Technology        : kbWordSearch kbWord97 kbWord97Search kbZNotKeyword2
Version           : WINDOWS:97
Issue type        : kbbug

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