How to read a CMake Variable in C++ source code

I'd like to store the version number of my library in just one place. So I have defined such a variable in the CMake-file:

    SET(LIBINTERFACE_VERSION 1 CACHE INTEGER "Version of libInterface")

With this definition I can generate a version.rc file according to Microsoft's definition, which I compile into the library and afterwards shows up correctly in the properties window of my dll-file.

Now I'd like to use this CMake variable in my c++ source code too, but I actually don't get to a working solution. I've tried different things like this:

    #ifndef VERSION_LIBINTERFACE
    #  define VERSION_LIBINTERFACE @LIBINTERFACE_VERSION@
    #endif

or this:

    unsigned int getLibInterfaceVersion()
    {
        return @LIBINTERFACE_VERSION@;
    }

But the compiler won't accept anything. Since my researches in the CMake-Documentation didn't get any results, I hope that someone could give me the essential advice.

Thanks in advance.