warnings returned by loadlibrary

I'm starting to learn MatLab, and as an exercise I'm using loadlibrary to call a function in a windows dll file. I've defined the header file according to the example in the help documentation, and called loadlibrary to load the external library. When I do I get multiple warnings about data types that do not exist. Some of the warnings say a data type used by a structure does not exist and some of the warnings say a data type used by a function does not exist.

How can I eliminate these warnings?

Here's the code snippet:

hfile = [matlabroot '\sys\lcc\include\mmsystem.h'];
loadlibrary ('winmm', hfile );
%define some variables
returnString = [];
returnStringLength = 0;
calllib ( 'winmm', 'mciSendStringA', 'set cdaudio door open', returnString, returnStringLength, 0);
Pause;
calllib ( 'winmm', 'mciSendStringA', 'set cdaudio door closed', returnString, returnStringLength, 0);
unloadlibrary winmm

As I said, it's just a really simple experiment in calling an external api. It opens the CD tray, waitss for me to press a key, then closes the tray. The code works, but I'd like to figure out the cause (and correct if I can) of the warnings.

...and now here's the warnings:

 Warning: Warnings messages were produced while parsing. Check the functions you intend to use for correctness. Warning text can be viewed using: [notfound,warnings]=loadlibrary(...)
 > In loadlibrary at 396
 In CDTray at 12
 Warning: The data type 's_wavehdrPtr' used by structure s_wavehdr does not exist. The structure may not be usable.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 's_midihdrPtr' used by structure s_midihdr does not exist. The structure may not be usable.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtrPtr' used by structure s_MMIOINFO does not exist. The structure may not be usable.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtrPtr' used by function mmioInstallIOProcA does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtrPtr' used by function mmioInstallIOProcW does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtr' used by function mciSetYieldProc does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtr' used by function mciGetYieldProc does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function waveOutGetPosition does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function waveInGetPosition does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetLineControlsA does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetLineControlsW does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetControlDetailsA does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetControlDetailsW does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function timeGetSystemTime does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'FcnPtrPtr' used by function timeSetEvent does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function midiStreamPosition does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetLineInfoA does not exist.
 > In loadlibrary at 458
 In CDTray at 12
 Warning: The data type 'error' used by function mixerGetLineInfoW does not exist.
 > In loadlibrary at 458
 In CDTray at 12

[Ashish Uthama]

Ading the exact test to your question might help. Maybe you forgot to include some header files that were used to compile the DLL.

[Ashish Uthama]

*text

[ryan]

http://www.mathworks.com/support/solutions/en/data/1-63MY7L/index.html?solution=1-63MY7L

I had the same problem, and found this very helpful

Answer 1

[Philip Borghesani]

The warnings can not be prevented when using a header that depends on windows.h but they can be suppressed by using:

warning off MATLAB:loadlibrary:TypeNotFound
warning off MATLAB:loadlibrary:TypeNotFoundForStructure
[notfound,warnings]=loadlibrary(libname,header,...);

See help for the function WARNING for more information of properly saving and restoring the warning state if desired.

For production code it is better to create a loader MATLAB file using the mfilename option to loadlibrary and edit that to remove unneeded functions and structures and to fix any errors in it. Loading a library is much faster when a loader file is used instead of a header.

Answer 2

[Patrick]

What do you mean with "can not be prevented when using a windows header"?

I use the mfilename option and also get warnings, that some data types not exists. Because of this I can not use some funtions of this library.

The same library compiled for linux works fine (with a linux system).

Thanks.

[Philip Borghesani]

Please post a new question for help with your problem.

To clarify for the purpose of this posting a windows header is one that depends on windows.h which defines many function and structures that can not be handled by loadlibrary.