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Q251344: BUG: CComBSTR::LoadString May Give an Access Violation

Article: Q251344
Product(s): Microsoft C Compiler
Version(s): WINDOWS:3.0,6.0
Operating System(s): 
Keyword(s): kbATL kbCOMt kbMFC kbString kbVC600bug kbATL300bug kbDSupport kbGrpDSMFCATL kbArchitect
Last Modified: 28-JUN-2001

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

- The Microsoft Active Template Library (ATL) 3.0, included with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

If you have used the CComBSTR class in a non-ATL application and used the bool
CComBSTR::LoadString(UINT nID) function, it might give an access violation.

CAUSE
=====

The global _pModule variable representing an instance of CComModule expected by
ATL, is not declared and initialized.

RESOLUTION
==========

Use the other overloaded version of LoadString that takes HINSTANCE as a
parameter

  bool CComBSTR::LoadString(HINSTANCE hInst, UINT nID)

and pass the HINSTANCE of the current module or the module wherever the string
resource is defined.

Or, add ATL support to this project. In order to add ATL support, from the Insert
menu, click New ATL Object. You are then asked if you want to add ATL support to
this project; click Yes. As a result, the ATL Object Wizard is opened. Cancel
that option if you do not want to add an ATL object to your project.

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. Generate a new MFC AppWizard SDI application.

2. Go to ResourceView and add a new string entry to the String Table resource
  and call it IDS_TESTSTRING.

3. Go to CYourApp::InitInstance and add the following code:

  CComBSTR bstrTemp;
  bstrTemp.LoadString(IDS_TESTSTRING);

4. Also add #include AtlBase.h to the .cpp file containing the above code for
  InitInstance.

5. Build and run it. You receive the access violation.

REFERENCES
==========

- Q175190 HOWTO: Add ATL Support to an MFC EXE

- CComModule

- CComBSTR

Additional query words: CString stringtable unexpected MFC

======================================================================
Keywords          : kbATL kbCOMt kbMFC kbString kbVC600bug kbATL300bug kbDSupport kbGrpDSMFCATL kbArchitecture 
Technology        : kbVCsearch kbAudDeveloper kbATLsearch
Version           : WINDOWS:3.0,6.0
Issue type        : kbbug
Solution Type     : kbpending

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

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