using calllib for 32 bit native module built in Microsoft Visual C++ 2008.

Hi,

I am working on a program that will call functions from a dynamic link library that was written in Microsoft Visual C++ 2008 and compiled in Microsoft Visual Studio 2008 as a 32 bit native module. Should I anticipate trouble using loadlib and calllib to access these functions on a 64 bit version of Matlab running on Windows 7? Will the 32 bit vs. 64 bit issue be a problem? Does loadlib and calllib work for C++ dll?

Thanks, Shennan

Answer 1

[James Tursa]

You can't mix 32-bit s/w and 64-bit s/w. You will not be able to call functions from a 32-bit dll from within a 64-bit application. You either need to recompile the lib as a 64-bit lib, or use a 32-bit version of MATLAB.

[Shennan Weiss]

If I use Matlab 2014 32 bit should I anticipate a problem because the dll was written in visual C++?

thanks Shennan

[James Tursa]

If the code is C++ and not C, did you use Extern "C" on the exported functions? The function interfaces will need to be C, not C++.

[Shennan Weiss]

I am showing my ignorance. Do you mean that I will only need to use extern C on the exported functions described in the header file for the dll?

Thanks Shennan

[James Tursa]

Yes. You can use C++ code all you want in the mex function, but the exported function signatures must be C. The function itself can use C++ code in the body, but its signature must be extern C for the interface in order to be able to use calllib on it. That, of course, means the dll must be compiled this way ... it is not sufficient to have a header h file for calllib to use with extern C if the dll was not compiled that way in the first place (since no such functions by that name would exist in the dll because of name mangling).