boost 获取当前日期和时间

#include <boost/date_time/gregorian/gregorian.hpp>    
#include <boost/date_time/posix_time/posix_time.hpp> 
#define BOOST_DATE_TIME_SOURCE  

boost::gregorian::to_iso_string(boost::gregorian::day_clock::local_day());

using namespace boost::posix_time;
using namespace boost::gregorian;
time_duration hms(second_clock::local_time().time_of_day());