Re: [Discuss-gnuradio] Multiple C files required by single C++ block.How to build?

[Jan Schiefer]

> Finally: “make clean”, “make” and “make check”.
>
> This results in:
>
> ImportError: 
> /home/jonas/gnuradio/gr-howto-write-a-block-3.0.2/src/lib/.libs/_howto.so: 
> undefined symbol: _Z10jonas_testv

What you need to do is to surround the declaration of jonas_testv() with 
en extern "C" {} declaration. If you don't do this, then the linker is 
looking for the "mangled name" , which is C++'s way to embed type 
declarations in a function name. If the function is declared in the .h 
as extern "C", it will just expect the function name with an underscore 
in front of it, just like C does.

Cheers,
  Jan