提升：如何从Epoch打印/转换posix_time :: ptime（以毫秒为单位）？

posix_time::ptime

time_t

posix_time::milliseconds

posix_time::ptime

void print_ptime_in_ms_from_epoch(const boost::posix_time::ptime& pt)
  {
    using boost::posix_time::ptime;
    using namespace boost::gregorian;
    std::cout << (pt-ptime(date(1941, Dec, 7))).total_milliseconds() << "n";
  }