Re: Geeting hash_map values back
On Jan 22, 6:35 pm, James Kanze <james.ka...@gmail.com> wrote:
On Jan 21, 3:07 pm, "C C++ C++" <m.azm...@gmail.com> wrote:
Several comments...
I have thread create function like this
pthread_create(&ThreadA,NULL,threadWork::requestThread,(void
*)&ResultSet); // <--- ResultSet is hasp_map with around 10 key-values
in it.
Is "threadWork" a namespace or a class? The third argument to
class
pthread_create must be a pointer to an `extern "C"'
function---member functions (even static) can't be `extern "C"',
and there's really no point in putting an `extern "C"' in a
namespace.
in threadWork.cc member function is defined
void * threadWork::requestThread(void *ResultSet)
{
cout << typeid(ResultSet).name() << ResultSet<<endl; // <<------ its
printing void * which is correct, how can i get my hash_map and its
values back ?
}
Use static_cast. With hash_map, there should be no problem. In
general, however, do be careful that you go through the right
types---something like:
extern "C" void*
threadFunction( void* p )
{
Base* args = static_cast< Base* >( p ) ;
// ...
}
// ...
Derived args ;
pthread_create( ..., &args ) ;
has undefined behavior. (The call to pthread_create should be:
pthread_create( ..., static_cast< Base* >( &args ) ) ;
fourth agument should be void *, how can you pass above one ?
And watch out for potential lifetime of object issues.)
--
James Kanze (GABI Software) mailto:james.ka...@gmail.com
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