Can I call an external shared library (DLL) from a MATLAB MEX-file?

I would like to call an external shared library (DLL) from a MATLAB MEX-file.

Answer 1

[MathWorks Support Team]

To link an external DLL to a MEX-file, list the DLL's .lib file on the command line.

Here is an example:

mex filename.c libname.lib

Note that when calling the MEX-file from MATLAB, the DLL should be in the same directory as the MEX-file.

[Qun Wu]

Thank you. This is how to link an external DLL, but how do I call some function in the DLL? And do I need to LoadLibrary the dll again in mex-file? Thanks.

[James Tursa]

You call functions from the lib file just like you would call any other function in your code. As long as the function is exported in the lib file, and you have included the appropriate prototypes in your source code (e.g. via a header file), there is nothing else special you need to do. LoadLibrary has nothing to do with this.

[Walter Roberson]

The link to f13120 is obsolete.

[Stefanie Schwarz]

@Walter I removed it. Thanks!

[Andrew Cunningham]

I am having some problems with this in Matlab 2018a/Windows 10. I have a MEX file that depends on a DLL, say, CCC.DLL. I placed this CCC.DLL into the same directory as the MEX DLL. I was having some issues with the MEX DLL not loading, and I used the Visual C++ debugger to see what DLLs were being loaded.

To my suprise I found that when the MEX DLL was loaded, a CCC.DLL that happened to be in the system PATH was being loaded before the CCC.DLL that was in the same directory as the MEX file. This seems contrary to the normal rules of LoadLibrary but things are not quite as simple as they use to be on Windows.

Furthermore, once I removed from the PATH the directory that contained the rogue CCC.DLL, I was able to verify that when the MEX DLL loaded, it also correctly loaded it's local CCC.DLL.