Examples

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### Examples

#### General Usage Examples

The following provides some sample usage of dates. See Date Programming for more details.

    	 using namespace boost::gregorian;
    	 date weekstart(2002,Feb,1);
    	 date weekend  = weekstart + week(1);
    	 date d2 = d1 + days(5);
    	 date today = day_clock::local_day();
    	 if (d2 >= today) {} //date comparison operators

    	 date_period thisWeek(d1,d2);
    	 if (thisWeek.contains(today)) {}//do something

    	 //iterate and print the week
    	 day_iterator itr(weekstart);
    	 while (itr <= weekend) {
    	   std::cout << (*itr) << std::endl;
               ++itr;
    	 }
             //input streaming
             std::stringstream ss("2004-Jan-1");
             ss >> d3;

             //localized i/o using facets
             std::locale global;
             std::locale german(global,
                                new date_facet(de_short_month_names,
                                               de_long_month_names,
                                               de_special_value_names,
                                               de_long_weekday_names,
                                               de_long_weekday_names,
                                               '.',
                                               boost::date_time::ymd_order_dmy));
             std::cout.imbue(global2);
             date d4(2002, Oct, 1);
             std::cout << d4; //01.Okt.2002

             //date generator functions
             date d5 = next_weekday(d4, Sunday); //calculate sunday following d4

             //define a shorthand for the nth_day_of_the_week_in_month function object
    	 typedef nth_day_of_the_week_in_month nth_dow;
             //US labor day is first Monday in Sept
    	 nth_dow labor_day(nth_dow::first,Monday, Sep);
    	 date d6 = labor_day.get_date(2004); //calculate a specific date from functor

The following provides some example code using times. See Time Programming for more details.

    	 use namespace boost::posix_time;
    	 date d(2002,Feb,1); //an arbitrary date
    	 ptime t1(d, hours(5)+nanosec(100)); //date + time of day offset
    	 ptime t2 = t1 - minutes(4)+seconds(2);
    	 ptime now = second_clock::local_time(); //use the clock
    	 date today = now.date(); //Get the date part out of the time
    	 date tommorrow = today + date_duration(1);
    	 ptime tommorrow_start(tommorrow); //midnight

             //input streaming
             std::stringstream ss("2004-Jan-1 05:21:33.20");
             ss >> t2;

    	 //starting at current time iterator adds by one hour
    	 time_iterator titr(now,hours(1));
    	 for (; titr < tommorrow_start; ++titr) {
    	   std::cout << (*titr) << std::endl;
    	 }

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#### Dates as Strings

Various parsing and output of strings.

          /* The following is a simple example that shows conversion of dates
           * to and from a std::string.
           *
           * Expected output:
           * 2001-Oct-09
           * 2001-10-09
           * Tuesday October 9, 2001
           * An expected exception is next:
           * Exception: Month number is out of range 1..12
           */

          #include "boost/date_time/gregorian/gregorian.hpp"
          #include <iostream>
          #include <string>

          int
          main()
          {

    	using namespace boost::gregorian;

    	try {
    	  // The following date is in ISO 8601 extended format (CCYY-MM-DD)
    	  std::string s("2001-10-9"); //2001-October-09
    	  date d(from_simple_string(s));
    	  std::cout << to_simple_string(d) << std::endl;

    	  //Read ISO Standard(CCYYMMDD) and output ISO Extended
    	  std::string ud("20011009"); //2001-Oct-09
    	  date d1(from_undelimited_string(ud));
    	  std::cout << to_iso_extended_string(d1) << std::endl;

    	  //Output the parts of the date - Tuesday October 9, 2001
    	  date::ymd_type ymd = d1.year_month_day();
    	  greg_weekday wd = d1.day_of_week();
    	  std::cout << wd.as_long_string() << " "
    		    << ymd.month.as_long_string() << " "
    		    << ymd.day << ", " << ymd.year
    		    << std::endl;

    	  //Let's send in month 25 by accident and create an exception
    	  std::string bad_date("20012509"); //2001-??-09
    	  std::cout << "An expected exception is next: " << std::endl;
    	  date wont_construct(from_undelimited_string(bad_date));
    	  //use wont_construct so compiler doesn't complain, but you wont get here!
    	  std::cout << "oh oh, you shouldn't reach this line: "
    		    << to_iso_string(wont_construct) << std::endl;
    	}
    	catch(std::exception& e) {
    	  std::cout << "  Exception: " <<  e.what() << std::endl;
    	}

    	return 0;
          }

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#### Days Alive

Calculate the number of days you have been living using durations and dates.

          /* Short example that calculates the number of days since user was born.
           * Demonstrates comparisons of durations, use of the day_clock,
           * and parsing a date from a string.
           */

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

          int
          main()
          {

    	using namespace boost::gregorian;
    	std::string s;
    	std::cout << "Enter birth day YYYY-MM-DD (eg: 2002-02-01): ";
    	std::cin >> s;
    	try {
    	  date birthday(from_simple_string(s));
    	  date today = day_clock::local_day();
    	  days days_alive = today - birthday;
    	  days one_day(1);
    	  if (days_alive == one_day) {
    	    std::cout << "Born yesterday, very funny" << std::endl;
    	  }
    	  else if (days_alive < days(0)) {
    	    std::cout << "Not born yet, hmm: " << days_alive.days()
    		      << " days" <<std::endl;
    	  }
    	  else {
    	    std::cout << "Days alive: " << days_alive.days() << std::endl;
    	  }

    	}
    	catch(...) {
    	  std::cout << "Bad date entered: " << s << std::endl;
    	}
    	return 0;
          }

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#### Days Between New Years

Calculate the number of days till new years

          /* Provides a simple example of using a date_generator, and simple
           * mathematical operatorations, to calculate the days since
           * New Years day of this year, and days until next New Years day.
           *
           * Expected results:
           * Adding together both durations will produce 366 (365 in a leap year).
           */
          #include <iostream>
          #include "boost/date_time/gregorian/gregorian.hpp"

          int
          main()
          {

    	using namespace boost::gregorian;

    	date today = day_clock::local_day();
    	partial_date new_years_day(1,Jan);
    	//Subtract two dates to get a duration
    	days days_since_year_start = today - new_years_day.get_date(today.year());
    	std::cout << "Days since Jan 1: " << days_since_year_start.days()
    		  << std::endl;

    	days days_until_year_start = new_years_day.get_date(today.year()+1) - today;
    	std::cout << "Days until next Jan 1: " << days_until_year_start.days()
    		  << std::endl;
    	return 0;
          };

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#### End of the Months

Iterates accross the remaining months in a given year, always landing on the last day of the month.

          /* Simple program that uses the gregorian calendar to find the last
           * day of the month and then display the last day of every month left
           * in the year.
           */

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

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

    	std::cout << "   Enter Year(ex: 2002): ";
    	int year, month;
    	std::cin >> year;
    	std::cout << "   Enter Month(1..12): ";
    	std::cin >> month;
    	try {
    	  int day = gregorian_calendar::end_of_month_day(year,month);
    	  date end_of_month(year,month,day);

    	  //Iterate thru by months --
    	  month_iterator mitr(end_of_month,1);
    	  date start_of_next_year(year+1, Jan, 1);
    	  //loop thru the days and print each one
    	  while (mitr < start_of_next_year){
    	    std::cout << to_simple_string(*mitr) << std::endl;
    	    ++mitr;
    	  }

    	}
    	catch(...) {
    	  std::cout << "Invalid Date Entered" << std::endl;
    	}
    	return 0;

          }

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#### Localization Demonstration

The boost::date_time library provides the ability to create customized locale facets. Date ordering, language, seperators, and abbreviations can be customized.

          /* The following shows the creation of a facet for the output of
           * dates in German (please forgive me for any errors in my German --
           * I'm not a native speaker).
           */

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

          /* Define a series of char arrays for short and long name strings to be
           * associated with date output. */
          const char* const de_short_month_names[] =
          {
    	"Jan", "Feb", "Mar", "Apr", "Mai", "Jun",
    	"Jul", "Aug", "Sep", "Okt", "Nov", "Dez", "NAM"
          };
          const char* const de_long_month_names[] =
          {
    	"Januar", "Februar", "Marz", "April", "Mai",
    	"Juni", "Juli", "August", "September", "Oktober",
    	"November", "Dezember", "NichtDerMonat"
          };
          const char* const de_special_value_names[] =
          {
    	"NichtDatumzeit", "-unbegrenztheit", "+unbegrenztheit"
          };
          const char* const de_long_weekday_names[] =
          {
    	"Sonntag", "Montag", "Dienstag", "Mittwoch",
    	"Donnerstag", "Freitag", "Samstag"
          };
          const char* const de_short_weekday_names[] =
          {
    	"Son", "Mon", "Die","Mit", "Don", "Fre", "Sam"
          };

          const char* const us_short_month_names[] =
          {
    	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
    	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "NAD"
          };
          const char* const us_long_month_names[] =
          {
    	"January", "February", "March", "April", "May",
    	"June", "July", "August", "September", "October",
    	"November", "December", "Not-A-Date"
          };
          const char* const us_special_value_names[] =
          {
    	"Not-A-Date", "-infinity", "+infinity"
          };
          const char* const us_long_weekday_names[] =
          {
    	"Sunday", "Monday", "Tuesday", "Wenesday",
    	"Thursday", "Friday", "Saturday"
          };
          const char* const us_short_weekday_names[] =
          {
    	"Sun", "Mon", "Tue","Wed", "Thu", "Fri", "Sat"
          };

          int
          main()
          {

          #ifndef BOOST_DATE_TIME_NO_LOCALE

    	using namespace boost::gregorian;
    	typedef boost::date_time::all_date_names_put<greg_facet_config> date_facet;

    	//create a new local
    	std::locale default_locale;
    	std::locale german_dates1(default_locale,
    				  new date_facet(de_short_month_names,
    						 de_long_month_names,
    						 de_special_value_names,
    						 de_short_weekday_names,
    						 de_long_weekday_names,
    						 '.',
    						 boost::date_time::ymd_order_dmy,
    						 boost::date_time::month_as_integer));

    	date d1(2002, Oct, 1);
    	std::cout.imbue(german_dates1);
    	// output the date in German using short month names
    	std::cout << d1 << std::endl; //01.10.2002

    	std::locale german_dates2(default_locale,
    				  new date_facet(de_short_month_names,
    						 de_long_month_names,
    						 de_special_value_names,
    						 de_short_weekday_names,
    						 de_long_weekday_names,
    						 '.',
    						 boost::date_time::ymd_order_dmy,
    						 boost::date_time::month_as_long_string));

    	std::cout.imbue(german_dates2);
    	greg_month m = d1.month();
    	std::cout << m << std::endl; //Oktober

    	greg_weekday wd = d1.day_of_week();
    	std::cout << wd << std::endl; //Dienstag

    	//Numeric date format with US month/day/year ordering
    	std::locale usa_dates1(default_locale,
    			       new date_facet(us_short_month_names,
    					      us_long_month_names,
    					      us_special_value_names,
    					      us_short_weekday_names,
    					      us_long_weekday_names,
    					      '/',
    					      boost::date_time::ymd_order_us,
    					      boost::date_time::month_as_integer));

    	std::cout.imbue(usa_dates1);
    	std::cout << d1 << std::endl; //  10/01/2002
    	//English names, iso order (year-month-day), '-' separator
    	std::locale usa_dates2(default_locale,
    			       new date_facet(us_short_month_names,
    					      us_long_month_names,
    					      us_special_value_names,
    					      us_short_weekday_names,
    					      us_long_weekday_names,
    					      '-',
    					      boost::date_time::ymd_order_iso,
    					      boost::date_time::month_as_short_string));

    	std::cout.imbue(usa_dates2);
    	std::cout << d1 << std::endl; //  2002-Oct-01

          #else
    	std::cout << "Sorry, localization is not supported by this compiler/library"
    		  << std::endl;
          #endif
    	return 0;

          }

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#### Date Period Calculations

Calculates if a date is in an 'irregular' collection of periods using period calculation functions.

          /*
          This example demonstrates a simple use of periods for the calculation
          of date information.

          The example calculates if a given date is a weekend or holiday
          given an exclusion set.  That is, each weekend or holiday is
          entered into the set as a time interval.  Then if a given date
          is contained within any of the intervals it is considered to
          be within the exclusion set and hence is a offtime.

          Output:
          Number Excluded Periods: 5
          20020202/20020203
          20020209/20020210
          20020212/20020212
          20020216/20020217
          In Exclusion Period: 20020216 --> 20020216/20020217
          20020223/20020224

          */

          #include "boost/date_time/gregorian/gregorian.hpp"
          #include <set>
          #include <algorithm>
          #include <iostream>

          typedef std::set<boost::gregorian::date_period> date_period_set;

          //Simple population of the exclusion set
          date_period_set
          generateExclusion()
          {
    	using namespace boost::gregorian;
    	date_period periods_array[] =
    	  { date_period(date(2002,Feb,2), date(2002,Feb,4)),//weekend of 2nd-3rd
    	    date_period(date(2002,Feb,9), date(2002,Feb,11)),
    	    date_period(date(2002,Feb,16), date(2002,Feb,18)),
    	    date_period(date(2002,Feb,23), date(2002,Feb,25)),
    	    date_period(date(2002,Feb,12), date(2002,Feb,13))//a random holiday 2-12
    	  };
    	const int num_periods = sizeof(periods_array)/sizeof(date_period);

    	date_period_set ps;
    	//insert the periods in the set
    	std::insert_iterator<date_period_set> itr(ps, ps.begin());
    	std::copy(periods_array, periods_array+num_periods, itr );
    	return ps;

          }

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

    	date_period_set ps = generateExclusion();
    	std::cout << "Number Excluded Periods: "  << ps.size() << std::endl;

    	date d(2002,Feb,16);
    	date_period_set::const_iterator i = ps.begin();
    	//print the periods, check for containment
    	for (;i != ps.end(); i++) {
    	  std::cout << to_iso_string(*i) << std::endl;
    	  //if date is in exclusion period then print it
    	  if (i->contains(d)) {
    	    std::cout << "In Exclusion Period: "
    		<< to_iso_string(d) << " --> " << to_iso_string(*i)
    		<< std::endl;
    	  }
    	}

    	return 0;

          }

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#### Print Holidays

This is an example of using functors to define a holiday schedule

          /* Generate a set of dates using a collection of date generators
           * Output looks like:
           * Enter Year: 2002
           * 2002-Jan-01 [Tue]
           * 2002-Jan-21 [Mon]
           * 2002-Feb-12 [Tue]
           * 2002-Jul-04 [Thu]
           * 2002-Sep-02 [Mon]
           * 2002-Nov-28 [Thu]
           * 2002-Dec-25 [Wed]
           * Number Holidays: 7
           */

          #include "boost/date_time/gregorian/gregorian.hpp"
          #include <algorithm>
          #include <functional>
          #include <vector>
          #include <iostream>
          #include <set>

          void
          print_date(boost::gregorian::date d)
          {
    	using namespace boost::gregorian;
          #if defined(BOOST_DATE_TIME_NO_LOCALE)
    	std::cout << to_simple_string(d) << " [" << d.day_of_week() << "]\n";
          #else
    	std::cout << d << " [" << d.day_of_week() << "]\n";
          #endif
          }

          int
          main() {

    	std::cout << "Enter Year: ";
    	int year;
    	std::cin >> year;

    	using namespace boost::gregorian;

    	//define a collection of holidays fixed by month and day
    	std::vector<year_based_generator*> holidays;
    	holidays.push_back(new partial_date(1,Jan)); //Western New Year
    	holidays.push_back(new partial_date(4,Jul)); //US Independence Day
    	holidays.push_back(new partial_date(25, Dec));//Christmas day

    	//define a shorthand for the nth_day_of_the_week_in_month function object
    	typedef nth_day_of_the_week_in_month nth_dow;

    	//US labor day
    	holidays.push_back(new nth_dow(nth_dow::first,  Monday,   Sep));
    	//MLK Day
    	holidays.push_back(new nth_dow(nth_dow::third,  Monday,   Jan));
    	//Pres day
    	holidays.push_back(new nth_dow(nth_dow::second, Tuesday,  Feb));
    	//Thanksgiving
    	holidays.push_back(new nth_dow(nth_dow::fourth, Thursday, Nov));

    	typedef std::set<date> date_set;
    	date_set all_holidays;

    	for(std::vector<year_based_generator*>::iterator it = holidays.begin();
    	    it != holidays.end(); ++it)
    	{
    	  all_holidays.insert((*it)->get_date(year));
    	}

    	//print the holidays to the screen
    	std::for_each(all_holidays.begin(), all_holidays.end(), print_date);
    	std::cout << "Number Holidays: " << all_holidays.size() << std::endl;

    	return 0;
          }

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#### Print Month

Simple utility to print out days of the month with the days of a month. Demontstrates date iteration (date_time::date_itr).

          /* This example prints all the dates in a month. It demonstrates
           * the use of iterators as well as functions of the gregorian_calendar
           *
           * Output:
           * Enter Year: 2002
           * Enter Month(1..12): 2
           * 2002-Feb-01 [Fri]
           * 2002-Feb-02 [Sat]
           * 2002-Feb-03 [Sun]
           * 2002-Feb-04 [Mon]
           * 2002-Feb-05 [Tue]
           * 2002-Feb-06 [Wed]
           * 2002-Feb-07 [Thu]
           */

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

          int
          main()
          {
    	std::cout << "Enter Year: ";
    	int year, month;
    	std::cin >> year;
    	std::cout << "Enter Month(1..12): ";
    	std::cin >> month;

    	using namespace boost::gregorian;
    	try {
    	  //Use the calendar to get the last day of the month
    	  int eom_day = gregorian_calendar::end_of_month_day(year,month);
    	  date endOfMonth(year,month,eom_day);

    	  //construct an iterator starting with firt day of the month
    	  day_iterator ditr(date(year,month,1));
    	  //loop thru the days and print each one
    	  for (; ditr <= endOfMonth; ++ditr) {
          #if defined(BOOST_DATE_TIME_NO_LOCALE)
    	    std::cout << to_simple_string(*ditr) << " ["
          #else
    	    std::cout << *ditr << " ["
          #endif
    		      << ditr->day_of_week() << "]"
    		      << std::endl;
    	  }
    	}
    	catch(std::exception& e) {

    	  std::cout << "Error bad date, check your entry: \n"
    		    << "  Details: " << e.what() << std::endl;
    	}
    	return 0;
          }

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#### Month Adding

Adding a month to a day without the use of iterators.

          /* Simple program that uses the gregorian calendar to progress by exactly
           * one month, irregardless of how many days are in that month.
           *
           * This method can be used as an alternative to iterators
           */

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

          int
          main()
          {

    	using namespace boost::gregorian;
    	typedef boost::date_time::month_functor<date> add_month;

    	date d = day_clock::local_day();
    	add_month mf(1);
    	date d2 = d + mf.get_offset(d);
    	std::cout << "Today is: " << to_simple_string(d) << ".\n"
    	  << "One month from today will be: " << to_simple_string(d2)
    	  << std::endl;

    	return 0;
          }

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#### 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;
          }

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#### Print Hours

Demonstrate time iteration, clock retrieval, and simple calculation.

          /* Print the remaining hours of the day
           * Uses the clock to get the local time
           * Use an iterator to iterate over the remaining hours
           * Retrieve the date part from a time
           *
           * Expected Output something like:
           *
           * 2002-Mar-08 16:30:59
           * 2002-Mar-08 17:30:59
           * 2002-Mar-08 18:30:59
           * 2002-Mar-08 19:30:59
           * 2002-Mar-08 20:30:59
           * 2002-Mar-08 21:30:59
           * 2002-Mar-08 22:30:59
           * 2002-Mar-08 23:30:59
           * Time left till midnight: 07:29:01
           */

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

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

    	//get the current time from the clock -- one second resolution
    	ptime now = second_clock::local_time();
    	//Get the date part out of the time
    	date today = now.date();
    	date tommorrow = today + days(1);
    	ptime tommorrow_start(tommorrow); //midnight

    	//iterator adds by one hour
    	time_iterator titr(now,hours(1));
    	for (; titr < tommorrow_start; ++titr) {
    	  std::cout << to_simple_string(*titr) << std::endl;
    	}

    	time_duration remaining = tommorrow_start - now;
    	std::cout << "Time left till midnight: "
    		  << to_simple_string(remaining) << std::endl;
    	return 0;
          }

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#### Local to UTC Conversion

Demonstrate utc to local and local to utc calculations including dst.

          /* Demonstrate conversions between a local time and utc
           * Output:
           *
           * UTC <--> New York while DST is NOT active (5 hours)
           * 2001-Dec-31 19:00:00 in New York is 2002-Jan-01 00:00:00 UTC time
           * 2002-Jan-01 00:00:00 UTC is 2001-Dec-31 19:00:00 New York time
           *
           * UTC <--> New York while DST is active (4 hours)
           * 2002-May-31 20:00:00 in New York is 2002-Jun-01 00:00:00 UTC time
           * 2002-Jun-01 00:00:00 UTC is 2002-May-31 20:00:00 New York time
           *
           * UTC <--> Arizona (7 hours)
           * 2002-May-31 17:00:00 in Arizona is 2002-Jun-01 00:00:00 UTC time
           */

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

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

    	//This local adjustor depends on the machine TZ settings-- highly dangerous!
    	typedef boost::date_time::c_local_adjustor<ptime> local_adj;
    	ptime t10(date(2002,Jan,1), hours(7));
    	ptime t11 = local_adj::utc_to_local(t10);
    	std::cout << "UTC <--> Zone base on TZ setting" << std::endl;
    	std::cout << to_simple_string(t11) << " in your TZ is "
    		  << to_simple_string(t10) << " UTC time "
    		  << std::endl;
    	time_duration td = t11 - t10;
    	std::cout << "A difference of: "
    		  << to_simple_string(td) << std::endl;

    	//eastern timezone is utc-5
    	typedef boost::date_time::local_adjustor<ptime, -5, us_dst> us_eastern;

    	ptime t1(date(2001,Dec,31), hours(19)); //5 hours b/f midnight NY time

    	std::cout << "\nUTC <--> New York while DST is NOT active (5 hours)"
    		  << std::endl;
    	ptime t2 =  us_eastern::local_to_utc(t1);
    	std::cout << to_simple_string(t1) << " in New York is "
    		  << to_simple_string(t2) << " UTC time "
    		  << std::endl;

    	ptime t3 = us_eastern::utc_to_local(t2);//back should be the same
    	std::cout << to_simple_string(t2) << " UTC is "
    		  << to_simple_string(t3) << " New York time "
    		  << "\n\n";

    	ptime t4(date(2002,May,31), hours(20)); //4 hours b/f midnight NY time
    	std::cout << "UTC <--> New York while DST is active (4 hours)" << std::endl;
    	ptime t5 = us_eastern::local_to_utc(t4);
    	std::cout << to_simple_string(t4) << " in New York is "
    		  << to_simple_string(t5) << " UTC time "
    		  << std::endl;

    	ptime t6 = us_eastern::utc_to_local(t5);//back should be the same
    	std::cout << to_simple_string(t5) << " UTC is "
    		  << to_simple_string(t6) << " New York time "
    		  << "\n" << std::endl;

    	//Arizona timezone is utc-7 with no dst
    	typedef boost::date_time::local_adjustor<ptime, -7, no_dst> us_arizona;

    	ptime t7(date(2002,May,31), hours(17));
    	std::cout << "UTC <--> Arizona (7 hours)" << std::endl;
    	ptime t8 = us_arizona::local_to_utc(t7);
    	std::cout << to_simple_string(t7) << " in Arizona is "
    		  << to_simple_string(t8) << " UTC time "
    		  << std::endl;

    	return 0;
          }

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#### Time Periods

Demonstrate some simple uses of time periods.

          /* Some simple examples of constructing and calculating with times
           * Returns:
           * [2002-Feb-01 00:00:00/2002-Feb-01 23:59:59.999999999] contains 2002-Feb-01 03:00:05
           * [2002-Feb-01 00:00:00/2002-Feb-01 23:59:59.999999999] intersected with
           * [2002-Feb-01 00:00:00/2002-Feb-01 03:00:04.999999999] is
           * [2002-Feb-01 00:00:00/2002-Feb-01 03:00:04.999999999]
           */

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

          using namespace boost::posix_time;
          using namespace boost::gregorian;

          //Create a simple period class to contain all the times in a day
          class day_period : public time_period
          {
          public:
    	day_period(date d) : time_period(ptime(d),//midnight
    					 ptime(d,hours(24)))
    	{}

          };

          int
          main()
          {

    	date d(2002,Feb,1); //an arbitrary date
    	//a period that represents a day
    	day_period dp(d);
    	ptime t(d, hours(3)+seconds(5)); //an arbitray time on that day
    	if (dp.contains(t)) {
    	  std::cout << to_simple_string(dp) << " contains "
    		    << to_simple_string(t)  << std::endl;
    	}
    	//a period that represents part of the day
    	time_period part_of_day(ptime(d, hours(0)), t);
    	//intersect the 2 periods and print the results
    	if (part_of_day.intersects(dp)) {
    	  time_period result = part_of_day.intersection(dp);
    	  std::cout << to_simple_string(dp) << " intersected with\n"
    		    << to_simple_string(part_of_day) << " is \n"
    		    << to_simple_string(result) << std::endl;
    	}

    	return 0;
          }

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