# Time Math

Various types of calculations with times and time durations.

      /* Some simple examples of constructing and calculating with times
       * Output:
       * 2002-Feb-01 00:00:00 - 2002-Feb-01 05:04:02.001000000 = -5:04:02.001000000
       */

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

      int
      main()
      {
        using namespace boost::posix_time;
        using namespace boost::gregorian;

        date d(2002,Feb,1); //an arbitrary date
        //construct a time by adding up some durations durations
        ptime t1(d, hours(5)+minutes(4)+seconds(2)+millisec(1));
        //construct a new time by subtracting some times
        ptime t2 = t1 - hours(5)- minutes(4)- seconds(2)- millisec(1);
        //construct a duration by taking the difference between times
        time_duration td = t2 - t1;

        std::cout << to_simple_string(t2) << " - "
                  << to_simple_string(t1) << " = "
                  << to_simple_string(td) << std::endl;

        return 0;
      }