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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;
}
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;
}
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;
};
Example that gets a month and a year from the user and finds the last day of each remaining month of that year.
/* Simple program that finds the last day of the given month,
* then displays the last day of every month left in the given year.
*/
#include "boost/date_time/gregorian/gregorian.hpp"
#include <iostream>
int
main()
{
using namespace boost::gregorian;
greg_year year(1400);
greg_month month(1);
// get a month and a year from the user
try {
int y, m;
std::cout << " Enter Year(ex: 2002): ";
std::cin >> y;
year = greg_year(y);
std::cout << " Enter Month(1..12): ";
std::cin >> m;
month = greg_month(m);
}
catch(bad_year by) {
std::cout << "Invalid Year Entered: " << by.what() << '\n'
<< "Using minimum values for month and year." << std::endl;
}
catch(bad_month bm) {
std::cout << "Invalid Month Entered" << bm.what() << '\n'
<< "Using minimum value for month. " << std::endl;
}
date start_of_next_year(year+1, Jan, 1);
date d(year, month, 1);
// add another month to d until we enter the next year.
while (d < start_of_next_year){
std::cout << to_simple_string(d.end_of_month()) << std::endl;
d += months(1);
}
return 0;
}
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>
#include <algorithm>
/* Define a series of char arrays for short and long name strings
* to be associated with German date output (US names will be
* retrieved from the locale). */
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_long_weekday_names[] =
{
"Sonntag", "Montag", "Dienstag", "Mittwoch",
"Donnerstag", "Freitag", "Samstag"
};
const char* const de_short_weekday_names[] =
{
"Son", "Mon", "Die","Mit", "Don", "Fre", "Sam"
};
int main()
{
using namespace boost::gregorian;
// create some gregorian objects to output
date d1(2002, Oct, 1);
greg_month m = d1.month();
greg_weekday wd = d1.day_of_week();
// create a facet and a locale for German dates
date_facet* german_facet = new date_facet();
std::cout.imbue(std::locale(std::locale::classic(), german_facet));
// create the German name collections
date_facet::input_collection_type short_months, long_months,
short_weekdays, long_weekdays;
std::copy(&de_short_month_names[0], &de_short_month_names[11],
std::back_inserter(short_months));
std::copy(&de_long_month_names[0], &de_long_month_names[11],
std::back_inserter(long_months));
std::copy(&de_short_weekday_names[0], &de_short_weekday_names[6],
std::back_inserter(short_weekdays));
std::copy(&de_long_weekday_names[0], &de_long_weekday_names[6],
std::back_inserter(long_weekdays));
// replace the default names with ours
// NOTE: date_generators and special_values were not replaced as
// they are not used in this example
german_facet->short_month_names(short_months);
german_facet->long_month_names(long_months);
german_facet->short_weekday_names(short_weekdays);
german_facet->long_weekday_names(long_weekdays);
// output the date in German using short month names
german_facet->format("%d.%m.%Y");
std::cout << d1 << std::endl; //01.10.2002
german_facet->month_format("%B");
std::cout << m << std::endl; //Oktober
german_facet->weekday_format("%A");
std::cout << wd << std::endl; //Dienstag
// Output the same gregorian objects using US names
date_facet* us_facet = new date_facet();
std::cout.imbue(std::locale(std::locale::classic(), us_facet));
us_facet->format("%m/%d/%Y");
std::cout << d1 << std::endl; // 10/01/2002
// English names, iso order (year-month-day), '-' separator
us_facet->format("%Y-%b-%d");
std::cout << d1 << std::endl; // 2002-Oct-01
return 0;
}
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;
}
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;
}
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;
}
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;
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;
}
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;
}
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;
}
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;
}
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;
}
Example usage of custom_time_zone as well as posix_time_zone.
/* A simple example for using a custom_time_zone and a posix_time_zone.
*/
#include "boost/date_time/local_time/local_time.hpp"
#include <iostream>
int
main()
{
using namespace boost;
using namespace local_time;
using namespace gregorian;
using posix_time::time_duration;
/***** custom_time_zone *****/
// create the dependent objects for a custom_time_zone
time_zone_names tzn("Eastern Standard Time", "EST",
"Eastern Daylight Time", "EDT");
time_duration utc_offset(-5,0,0);
dst_adjustment_offsets adj_offsets(time_duration(1,0,0),
time_duration(2,0,0),
time_duration(2,0,0));
// rules for this zone are:
// start on first Sunday of April at 2 am
// end on last Sunday of October at 2 am
// so we use a first_last_dst_rule
first_day_of_the_week_in_month start_rule(Sunday, Apr);
last_day_of_the_week_in_month end_rule(Sunday, Oct);
shared_ptr<dst_calc_rule> nyc_rules(new first_last_dst_rule(start_rule,
end_rule));
// create more dependent objects for a non-dst custom_time_zone
time_zone_names tzn2("Mountain Standard Time", "MST",
"", ""); // no dst means empty dst strings
time_duration utc_offset2(-7,0,0);
dst_adjustment_offsets adj_offsets2(time_duration(0,0,0),
time_duration(0,0,0),
time_duration(0,0,0));
// no dst means we need a null pointer to the rules
shared_ptr<dst_calc_rule> phx_rules;
// create the custom_time_zones
time_zone_ptr nyc_1(new custom_time_zone(tzn, utc_offset,
adj_offsets, nyc_rules));
time_zone_ptr phx_1(new custom_time_zone(tzn2, utc_offset2,
adj_offsets2, phx_rules));
/***** posix_time_zone *****/
// create posix_time_zones that are the duplicates of the
// custom_time_zones created above. See posix_time_zone documentation
// for details on full zone names.
std::string nyc_string, phx_string;
nyc_string = "EST-05:00:00EDT+01:00:00,M4.1.0/02:00:00,M10.5.0/02:00:00";
// nyc_string = "EST-05EDT,M4.1.0,M10.5.0"; // shorter when defaults used
phx_string = "MST-07"; // no-dst
time_zone_ptr nyc_2(new posix_time_zone(nyc_string));
time_zone_ptr phx_2(new posix_time_zone(phx_string));
/***** show the sets are equal *****/
std::cout << "The first zone is in daylight savings from:\n "
<< nyc_1->dst_local_start_time(2004) << " through "
<< nyc_1->dst_local_end_time(2004) << std::endl;
std::cout << "The second zone is in daylight savings from:\n "
<< nyc_2->dst_local_start_time(2004) << " through "
<< nyc_2->dst_local_end_time(2004) << std::endl;
std::cout << "The third zone (no daylight savings):\n "
<< phx_1->std_zone_abbrev() << " and "
<< phx_1->base_utc_offset() << std::endl;
std::cout << "The fourth zone (no daylight savings):\n "
<< phx_2->std_zone_abbrev() << " and "
<< phx_2->base_utc_offset() << std::endl;
return 0;
}
Example of creating various Daylight Savings Calc Rule objects.
/* A simple example for creating various dst_calc_rule instances
*/
#include "boost/date_time/gregorian/gregorian.hpp"
#include "boost/date_time/local_time/local_time.hpp"
#include <iostream>
int
main()
{
using namespace boost;
using namespace local_time;
using namespace gregorian;
/***** create the necessary date_generator objects *****/
// starting generators
first_day_of_the_week_in_month fd_start(Sunday, May);
last_day_of_the_week_in_month ld_start(Sunday, May);
nth_day_of_the_week_in_month nkd_start(nth_day_of_the_week_in_month::third,
Sunday, May);
partial_date pd_start(1, May);
// ending generators
first_day_of_the_week_in_month fd_end(Sunday, Oct);
last_day_of_the_week_in_month ld_end(Sunday, Oct);
nth_day_of_the_week_in_month nkd_end(nth_day_of_the_week_in_month::third,
Sunday, Oct);
partial_date pd_end(31, Oct);
/***** create the various dst_calc_rule objects *****/
dst_calc_rule_ptr pdr(new partial_date_dst_rule(pd_start, pd_end));
dst_calc_rule_ptr flr(new first_last_dst_rule(fd_start, ld_end));
dst_calc_rule_ptr llr(new last_last_dst_rule(ld_start, ld_end));
dst_calc_rule_ptr nlr(new nth_last_dst_rule(nkd_start, ld_end));
dst_calc_rule_ptr ndr(new nth_day_of_the_week_in_month_dst_rule(nkd_start,
nkd_end));
return 0;
}
This example shows a program that calculates the arrival time of a plane that flys from Phoenix to New York. During the flight New York shifts into daylight savings time (Phoenix doesn't because Arizona doesn't use dst).
#include "boost/date_time/local_time/local_time.hpp"
#include <iostream>
/* This example shows a program that calculates the arrival time of a plane
* that flys from Phoenix to New York. During the flight New York shifts
* into daylight savings time (Phoenix doesn't because Arizona doesn't use
* dst).
*
*
*/
int main()
{
using namespace boost::gregorian;
using namespace boost::local_time;
using namespace boost::posix_time;
//setup some timezones for creating and adjusting local times
//This user editable file can be found in libs/date_time/data.
tz_database tz_db;
tz_db.load_from_file("date_time_zonespec.csv");
time_zone_ptr nyc_tz = tz_db.time_zone_from_region("America/New_York");
//Use a
time_zone_ptr phx_tz(new posix_time_zone("MST-07:00:00"));
//local departure time in phoenix is 11 pm on april 2 2005
// (ny changes to dst on apr 3 at 2 am)
local_date_time phx_departure(date(2005, Apr, 2), hours(23),
phx_tz,
local_date_time::NOT_DATE_TIME_ON_ERROR);
time_duration flight_length = hours(4) + minutes(30);
local_date_time phx_arrival = phx_departure + flight_length;
local_date_time nyc_arrival = phx_arrival.local_time_in(nyc_tz);
std::cout << "departure phx time: " << phx_departure << std::endl;
std::cout << "arrival phx time: " << phx_arrival << std::endl;
std::cout << "arrival nyc time: " << nyc_arrival << std::endl;
}
Example of calculating seconds elapsed since epoch (1970-Jan-1) using local_date_time.
/* This example demonstrates the use of the time zone database and
* local time to calculate the number of seconds since the UTC
* time_t epoch 1970-01-01 00:00:00. Note that the selected timezone
* could be any timezone supported in the time zone database file which
* can be modified and updated as needed by the user.
*
* To solve this problem the following steps are required:
* 1) Get a timezone from the tz database for the local time
* 2) Construct a local time using the timezone
* 3) Construct a posix_time::ptime for the time_t epoch time
* 4) Convert the local_time to utc and subtract the epoch time
*
*/
#include "boost/date_time/local_time/local_time.hpp"
#include <iostream>
int main()
{
using namespace boost::gregorian;
using namespace boost::local_time;
using namespace boost::posix_time;
tz_database tz_db;
try {
tz_db.load_from_file("../data/date_time_zonespec.csv");
}catch(data_not_accessible dna) {
std::cerr << "Error with time zone data file: " << dna.what() << std::endl;
exit(EXIT_FAILURE);
}catch(bad_field_count bfc) {
std::cerr << "Error with time zone data file: " << bfc.what() << std::endl;
exit(EXIT_FAILURE);
}
time_zone_ptr nyc_tz = tz_db.time_zone_from_region("America/New_York");
date in_date(2004,10,04);
time_duration td(12,14,32);
// construct with local time value
// create not-a-date-time if invalid (eg: in dst transition)
local_date_time nyc_time(in_date,
td,
nyc_tz,
local_date_time::NOT_DATE_TIME_ON_ERROR);
std::cout << nyc_time << std::endl;
ptime time_t_epoch(date(1970,1,1));
std::cout << time_t_epoch << std::endl;
// first convert nyc_time to utc via the utc_time()
// call and subtract the ptime.
time_duration diff = nyc_time.utc_time() - time_t_epoch;
//Expected 1096906472
std::cout << "Seconds diff: " << diff.total_seconds() << std::endl;
}