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Q166817: FIX: Alpha MFC Regular DLL Fails After Porting from Intel

Article: Q166817
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,4.0a
Operating System(s): 
Keyword(s): kbDLL kbide kbMFC kbVC400bug kbVC500fix kbGrpDSTools kbNoUpdate
Last Modified: 07-MAY-2001

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

- Microsoft Visual C++, versions 4.0, 4.0a, on platform(s):
   - the hardware: DEC Alpha 
-------------------------------------------------------------------------------

SYMPTOMS
========

When moving a Visual C++ 4.x MFC regular DLL (_USRDLL) project from the Intel
platform to the Alpha RISC platform you may run into one or more of a set of
related problems. Some symptoms are:

- CWinApp::InitInstance() is not called.

- Resources stored in the DLL fail to load because AfxGetResourceHandle or
  AfxFindResourceHandle returns NULL or an incorrect resource handle.

- AfxGetInstanceHandle() returns NULL.

- Standard MFC database, sockets, or OLE resources fail to load. For example,
  AfxLoadString(AFX_IDP_SQL_CONNECT_FAIL) returns an empty string, even when
  the Regular DLL is properly using the MFC Database classes.

CAUSE
=====

When you create the Alpha configuration from an existing Intel based
configuration, the Visual C++ development environment does not copy the /D
_USRDLL compiler flag. This problem does not cause compiler or linker errors.

Without this symbol defined, the default non-MFC DllMain is used and MFC is not
initialized.

RESOLUTION
==========

Make sure that /D "_USRDLL" is in the compiler options for regular MFC DLLs. If
not, add _USRDLL to the list of preprocessor definitions.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 5.0.

REFERENCES
==========

For more information covering MFC initialization in your Regular DLL, and other
relevant topics, please see the following articles in the Microsoft Knowledge
Base:

  Q140850 HOWTO: Properly Export Functions Using the MFC Shared Library

  Q154126 PRB: Using Extension DLL, Database/OLE/Sockets in Regular DLL

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Kelly Marie
Ward, Microsoft Corporation


Additional query words: 4.1 4.2B AXP Digital

======================================================================
Keywords          : kbDLL kbide kbMFC kbVC400bug kbVC500fix kbGrpDSTools kbNoUpdate 
Technology        : kbVCsearch kbAudDeveloper
Version           : winnt:4.0,4.0a
Issue type        : kbbug
Solution Type     : kbfix

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