DOCUMENT:Q194617  03-NOV-1998  [vbwin]
TITLE   :FIX: ReDim Preserve Fails on Uninitialized Arrays
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:6.0
OPER/SYS:WINDOWS
KEYWORDS:

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

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

SYMPTOMS
========

After you've used Redim Preserve to re-dimension a dynamic array and run
the application, it terminates with the following error:

   "Runtime Error 5: "Invalid Procedure Call or Argument".

CAUSE
=====

You cannot use Redim Preserve on a dynamic array that has not been
initialized.

RESOLUTION
==========

The workaround is to check the value of the upper bound of the array and ,
if it is not initialized (the upper bound will have a value of -1), use a
Redim statement without Preserve. Below is the sample code that
demonstrates this workaround:

   a = Array()
   b = UBound(a)           'get value of largest available array subscript

   If (b <> -1) Then       '-1 is the return value of a uninitialize array
       ReDim Preserve a(5)
   Else
       ReDim a(5)          'no elements exist in array use ReDim
   End If

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. This bug has been corrected in Microsoft
Visual Basic Learning, Professional, and Enterprise Editions for Windows,
version 6.0, Service Pack 1.

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

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

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

2. Place a CommandButton on Form1 and paste the following code:

      Private Sub Command1_Click()
         Dim a As Variant
         a = Array()
         ReDim Preserve a(5)
      End Sub

3. Press the F5 key to run the application, and note that the above error
   appears.

Additional query words: kbDSupport kbVBp600 kbVS600SP1fix kbNoKeyWord
======================================================================
Version           : WINDOWS:6.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix

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

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