BUG: C4003: Not Enough Parameters for SubclassWindow Macro

• Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52, 1.52a
• Microsoft Visual C++, 32-bit Edition, versions 1.0, 2.0, 2.1, 2.2, 4.0, 4.1

SYMPTOMS

When compiling a Microsoft Foundation Class (MFC) application that uses the Windowsx.h header file and calls CWnd::SubclassWindow(), you may get the following error:

   warning C4003: not enough actual parameters for macro 'SubclassWindow'
   error C2059: syntax error : ')'

CAUSE

The Windowsx.h file is a header that includes message cracker macros to help programmers write more portable Windows-based applications. The header file contains a preprocessor macro named SubclassWindow. The macro bears the same name as the CWnd::SubclassWindow() member function. The macro has two parameters; the member function has only one parameter. The preprocessor tries to expand the symbol SubclassWindow when it is found.

RESOLUTION

You can un-define the macro as follows:

   #undef SubclassWindow

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

REFERENCES

Win32 SDK Books Online. MFC Class Library Reference.