Question

i have a void pointer

void *vp;

I want to point it to vec_A inside a function where vec_A is passed as a reference, that is

some_function(std::vector<boost::shared_ptr<A> >& vec_A)
{
   void *vp;
   //now i want vp to point to vec_A
}

and after I point vp to vec_A, how to I get it back as

 std::vector<boost::shared_ptr<A> > 

Answer 1

Address-of and cast:

void * vp = &vec_A;   // address-of

std::vector< boost::shared_ptr<A> > & v =
     *static_cast< std::vector< boost::shared_ptr<A> >* >(vp);

Now v is a reference to the very same vector whose address you took in the line above.