Q197190: BUG: Memory Leak Using UBound or LBound When Returning Array

Article: Q197190
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbnokeyword kbVBp600bug kbGrpDSVB
Last Modified: 11-JAN-2001

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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 
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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.

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

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