DOCUMENT:Q197190  11-JAN-2001  [vbwin]
TITLE   :BUG: Memory Leak Using UBound or LBound When Returning Array
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:6.0
OPER/SYS:
KEYWORDS:kbnokeyword kbVBp600bug kbGrpDSVB

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Learning Edition for Windows, version 6.0 
 - Microsoft Visual Basic Professional Edition for Windows, version 6.0 
 - Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you use a function that returns an array as a parameter to the UBound or
LBound functions, the memory allocated for the array is not released.

CAUSE
=====

The array is copied to temporary return storage, but the temporary storage is
not released until the application ends.

RESOLUTION
==========

To avoid this problem, assign the return value to a local variable before using
UBound or LBound. For example:

      vntReturn = ArryFunc()
      iAryLen = UBound(vntReturn)

STATUS
======

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

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

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

1. Create a New Standard EXE project in Visual Basic. Form1 is created by
   default.

2. Add a CommandButton (Command1) to Form1.

3. Add the following code to Form1:

         Public Sub Command1_Click()
            iAryLen = UBound(ArryFunc())
         End Sub

4. Add a standard Module to the project and add the following code:

         Public Function ArryFunc() as Long ()
            Dim x(100000) as Long
            ArryFunc = x
         End Function

5. Run the project.

RESULT: When you click the button, it leaks ~400k with each click.

======================================================================
Keywords          : kbnokeyword kbVBp600bug kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : WINDOWS:6.0
Issue type        : kbbug
Solution Type     : kbpending

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.