Re: [Boost-users] [Thread] this_tread::sleep won't compile with gcc, "no match for operator+"

Basically, what I'm trying to do is:

    using namespace boost::posix_time;     using namespace boost::this_thread;

    time_duration td = milliseconds(2000);     sleep(&td);

Just curious: what's the purpose of the ampersand here? http://www.boost.org/doc/libs/1_46_1/doc/html/thread/thread_management.html#...