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Q134405: PRB: WaveOutOpen()/WaveInOpen() Returns MMSYSERR_INVALPARAM

Article: Q134405
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1; winnt:
Operating System(s): 
Keyword(s): kbprb
Last Modified: 08-MAY-2001

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

- Microsoft Windows Software Development Kit (SDK) 3.1 
- The Microsoft Foundation Classes (MFC), included with:
   - Microsoft Visual C++ 
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SYMPTOMS
========

The WaveOutOpen() and WaveInOpen() functions return an MMSYSERR_INVALPARAM error
when using a window handle as a callback mechanism.

CAUSE
=====

The documentation for the WaveOutOpen() and WaveInOpen() functions specifies
that the data type of the dwCallback parameter should be a DWORD. However, when
the symbol STRICT is defined (using #define), HWND is no longer equated to UINT.
Instead, it is a NEAR pointer. Therefore, simply casting a window handle to a
DWORD fails when STRICT is defined. The following code illustrates the statement
causing this error:

     WaveOutOpen(..., (DWORD) hWnd, ..., CALLBACK_WINDOW)

RESOLUTION
==========

A simple workaround is to cast a window handle to UINT before casting it to a
DWORD. For example:

     WaveOutOpen(..., (DWORD) (UINT) hWnd, ...)

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

STRICT is a macro which enhances type safety for Windows 3.1 applications. If it
is defined, several data types become distinct. For instance, HDC and HWND
become different types when STRICT is defined.

By default, Microsoft Foundation Classes (MFC) versions 2.0 and above use STRICT
type checking. As a result, the problem described in this article usually occurs
in MFC-based applications. In addition, this error occurs in any API call where
a window handle is cast to a DWORD (32-bits). Please note that this article only
applies to 16-bit applications.

Additional query words: 2.00 3.10 wave audio invalid window

======================================================================
Keywords          : kbprb 
Technology        : kbAudDeveloper kbMFC kbSDKSearch kbWinSDKSearch
Version           : WINDOWS:3.1; winnt:
Issue type        : kbprb

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

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