Q242588: BUG: VTS_UI1 and VTS_PUI1 are Defined Incorrectly in AfxDisp.h

Article: Q242588
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbAutomation kbCOMt kbMFC kbVC400bug kbVC410 kbVC420 kbVC500bug kbVC600bug kbDSupport k
Last Modified: 02-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), included with:
   - Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

When using the string literals defined for VTS_UI1 or VTS_PUI1 in calling
COleDispatchDriver::InvokeHelper() or CWnd::InvokeHelper(), you might get
strange results. You might notice any of the following symptoms when using the
values defined in AfxDisp.h:

- An ASSERT on line 321 in file Oledisp2.cpp in the
  COleDispatchDriver::InvokeHelperV function.

- A message box stating "Bad variable type."

- An uncaught exception in WindowProc.

- A first chance exception in Kernel32.dll.

CAUSE
=====

This is because VTS_UI1 and VTS_PUI1 are defined incorrectly in the Afxdisp.h
header file.

RESOLUTION
==========

Do not use VTS_UI1 or VTS_PUI1 in any of your code. Instead, define the correct
values for each of these using a name you assign. Code like the following can be
used:

  //Do NOT use VTS_UI1. It has a value of "0x0F" which is incorrect.
  //The correct value for VTS_UI1 is 17 or 0x11
  #define MY_VTS_UI1 "\x11"

  //Do NOT use VTS_PUI1. It has a value of "0x4F" which is incorrect.
  //The correct value for VTS_PUI1 is 81 or 0x51
  #define MY_VTS_PUI1 "\x51"

  void SomeFunction(BYTE byteVal)
  {
   static BYTE parms[] = MY_VTS_UI1; // please note that this is not VTS_UI1
   DISPID dispid = 0x60030000;       // notice that this is different!

   COleDispatchDriver d;
   if (d.CreateDispatch("SomeComObject.SomeComObject.1))
      d.InvokeHelper(dispid, DISPATCH_METHOD, VT_EMPTY, NULL, parms, byteVal);
  }

STATUS
======

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

REFERENCES
==========

  Q241862 BUG: ClassWizard Omits Methods that Take BYTE or BYTE* as Parameters

Additional query words: 0x80020008 COleException InvokeHelper Invoke IDispatch OLE Automation

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Keywords          : kbAutomation kbCOMt kbMFC kbVC400bug kbVC410 kbVC420 kbVC500bug kbVC600bug kbDSupport kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug

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