DOCUMENT:Q192745  17-SEP-1998  [vbwin]
TITLE   :HOWTO: Use CreateObject with Visual C++ COM Objects
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:5.0,6.0
OPER/SYS:WINDOWS
KEYWORDS:

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The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, versions 5.0, 6.0
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SUMMARY
=======

This article explains how to use CreateObject with COM/ActiveX components
created in Visual C++. The CreateObject programming syntax used to create
an instance of a component created in Visual Basic may not work with a VC++
component, even though the object can be created using the New method. For
example, assume you have an component named "neuLib" referenced in a Visual
Basic project. The component has one createable object (Interface) named
"myclass." The following code will work if the ActiveX component was
created using either Visual Basic or Visual C++:

   Dim objNeu as neuLib.myclass
   Set objNeu =  New neuLib.myclass

However, the code below will work only for a component created using Visual
Basic:

   Dim objNeu as neuLib.myclass
   Set objNeu = CreateObject("neuLib.myclass")

If this is a VC++-created component, you will receive the error message:

   "Error 429. ActiveX component can't create object."

The reason CreateObject works with a Visual Basic component and not with a
Visual C++ component can be explained and resolved by examining the
different way in which Visual Basic and Visual C++ create program IDs
(ProgID.) When you use CreateObject, the argument you provide is a ProgID.
Visual Basic and Visual C++  assign a name to the ProgID differently.
Visual Basic uses the original name, Visual C++ does not. In a Visual Basic
component, the ProgID for this example is "neuLib.myclass." In a Visual C++
component, the ProgID would be "myclass.myclass.1," which requires the
(correct) syntax:

   Dim objNeu as neuLib.myclass
   Set objNeu = CreateObject("myclass.myclass.1")

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

There are two ways to determine the ProgID that you need to specify when
using CreateObject for the VC object.

1. Use the OLE/Com Viewer. If you have this utility installed, start it and
   open the Visual C++  component. From the View menu, select Expert Mode.
   Select "All Objects" from the list in the left portion of the window.
   Scroll until you find the name of the class, then and click it. The
   detail window on the right should display the information about the
   class; the ProgID will be listed with this information, and will look
   like:

      ProgID = myclass.myclass.1

2. Use the Registry Editor (Regedit.exe). Click on the Start button and
   select Run. Type "Regedit" and click OK. From the Edit menu in Regedit,
   choose Find. Enter the name of the class, and make sure that "Data" is
   the only check box selected. Click OK.

   It is difficult to provide exact instructions for searching the
   Registry. The entry you are looking for will probably be the second one
   that is found (press the F3 key to resume searching.) When the data for
   the key is found, look in the window on the left half of the Regedit
   screen. If the tree node that is open says "ProgID," and the data in the
   window on the right contains the class name, then this is the value you
   want to use as the argument for CreateObject.

Additional query words: kbDSupport kbDSD kbVBp kbVBp500 kbVBp600 kbCtrl
kbActiveX kbCOMt
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Version           : WINDOWS:5.0,6.0
Platform          : WINDOWS
Issue type        : kbhowto

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