Question

If I create a struct:

struct joinpoint_exception: exception
{

   virtual const char* what () const throw ();
};

What does what () const throw () means in this context?

Answer 1

what is a virtual member function returning a pointer to constant char which is itself constant and throws nothing.

virtual const char* what () const throw ();
|-----| <- virtual member function
        |---------| <- returning a pointer to constant chars
                    |-----| <- named what
                            |---| <- which is constant
                                  |-------| <- which does not throw

(Technically the function can still throw, but if it does, it goes directly to std::unexpected, which defaults to calling std::terminate)