Connecting binary & php together

Hi I'm thinking about the best way to connect a c(++) binary with the php interpreter. I thought the best solution is to use a shared library which has been built by php. Is libphp4.so always the same or are the libraries for apache / apache2 / roxen / etc different ? I think the parameter --with-apxs or whatever is just given so that php knows what it has to do, right ? -- I won't pay Bill's