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Q122306: PRB: Error C4226 and Defining WIN32

Article: Q122306
Product(s): Microsoft C Compiler
Version(s): 2.0
Operating System(s): 
Keyword(s): kbprb
Last Modified: 29-JUL-2001

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The information in this article applies to:

- Microsoft Visual C++, version 2.0 
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SYMPTOMS
========

Compiling a source file that includes WINDOWS.H generates many C4226 errors,
such as:

  C:\MSVC20\INCLUDE\olebase.h (8954) : error C4226: nonstandard extension used
  : '__export' is an obsolete keyword

  ...

  C:\MSVC20\INCLUDE\oleauto.h(293) : error C4226: nonstandard extension used :
  '__huge' is an obsolete keyword

  ...

  C:\MSVC20\INCLUDE\ole2.h(4818) : error C4226: nonstandard extension used :
  '__export' is an obsolete keyword

Including these header files individually causes the same problem.

CAUSE
=====

A number of the OLE header files that are included in the WINDOWS.H file require
WIN32 to be defined. While _WIN32 is defined for you, WIN32 is not. Because
WIN32 is not defined, the header file logic assumes that the definitions are for
16-bit Windows-based applications and uses the __export and __huge keywords.

RESOLUTION
==========

Here are three possible way to define WIN32:

- Define WIN32 before the WINDOWS.H file is included.

     #define WIN32
     #include <windows.h>

- Define WIN32 in a compiler switch. From the command line, use /DWIN32. In the
  development environment, follow these following steps:

  1. Choose Settings from the Projects menu, and click the C/C++ tab.

  2. Select the Preprocessor category.

  3. Add WIN32 to the Preprocessor Definitions field of the dialog box.

- Add the following lines to the beginning of the WINDOWS.H file:

     #if( defined (_WIN32) && !defined (WIN32) )
     #define WIN32
     #endif

  NOTE: This will not take care of the case where individual OLE header files
  are included in an application.

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

This problem will most likely occur when building console applications.

NOTE: Although this was by design, this behavior was changed in Microsoft Visual
C++, 32-bit Edition, version 4.0.

Additional query words: 2.00

======================================================================
Keywords          : kbprb 
Technology        : kbVCsearch kbAudDeveloper kbVC200
Version           : :2.0
Issue type        : kbprb

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