boost擷取系統時間(毫秒級)

常用到的一段用boost讀系統時間的代碼：

#include <boost/date_time/posix_time/posix_time.hpp>

        // Get current time from the clock, using microseconds resolution
       const boost::posix_time::ptime now = boost::posix_time::microsec_clock::local_time();
       // Get the time offset in current day
       const boost::posix_time::time_duration td = now.time_of_day();
       int hh = td.hours();
       int mm = td.minutes();
       int ss = td.seconds();
       int ms = td.total_milliseconds() - ((hh * 3600 + mm * 60 + ss) * 1000);