linking libraries

[jacek]

I found the problem! It is my bad actually, the Vortex library is a C library, not a C++ library.

Then you should use Vortex headers like this:

extern "C" {
#include <vortex.h>
};

extern "C" {
#include <vortex.h>
};

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Athough it's strange that Vortex authors didn't take care of it.