Date Generators/Algorithms Introduction -- Header -- Class Overview -- Function Overview Introduction Date algorithms or generators are tools for generating other dates or schedules of dates. A generator function starts with some part of a date such as a month and day and is supplied another part to then generate a concrete date. This allows the programmer to represent concepts such as "The first Sunday in February" and then create a concrete set of dates when provided with one or more years. Note: As of boost version 1_31_0, date generator names have been changed. Old names are still available but are no longer documented and may someday be deprecated Also provided are stand-alone functions for generating a date, or calculation a duration of days. These functions take a date object and a weekday object as parameters. All date generator classes and functions are in the boost::gregorian namespace. The print holidays example shows a detailed usage example. Header #include "boost/date_time/gregorian/gregorian.hpp" Overview Class and get_date Parameter Description Example year_based_generator date get_date(greg_year year) A unifying (abstract) date_generator base type for: partial_date, nth_day_of_the_week_in_month, first_day_of_the_week_in_month, and last_day_of_the_week_in_month. The print holidays example shows a detailed usage example. last_day_of_the_week_in_month(greg_weekday, greg_month) date get_date(greg_year year) Calculate something like last Monday of January last_day_of_the_week_in_month lwdm(Monday,Jan); date d = lwdm.get_date(2002); //2002-Jan-28 first_day_of_the_week_in_month(greg_weekday, greg_month) date get_date(greg_year year) Calculate something like first Monday of January first_day_of_the_week_in_month fdm(Monday,Jan); date d = fdm.get_date(2002); //2002-Jan-07 nth_day_of_the_week_in_month(week_num, greg_weekday, greg_month) date get_date(greg_year year) week_num is a public enum member of nth_day_of_the_week_in_month. Calculate something like first Monday of January, second Tuesday of March, Third Sunday of December, etc. (first through fifth are provided, fifth is the equivalent of last) typedef nth_day_of_the_week_in_month nth_dow; nth_dow ndm(nth_dow::third, Monday,Jan); date d = ndm.get_date(2002); //2002-Jan-21 partial_date(greg_day, greg_month) date get_date(greg_year year) Generates a date by applying the year to the given month and day. partial_date pd(1,Jan); date d = pd.get_date(2002); //2002-Jan-01 first_day_of_the_week_after(greg_weekday) date get_date(date d) Calculate something like First Sunday after Jan 1,2002 first_day_of_the_week_after fdaf(Monday); date d = fdaf.get_date(date(2002,Jan,1)); //2002-Jan-07 first_day_of_the_week_before(greg_weekday) date get_date(date d) Calculate something like First Monday before Feb 1,2002 first_day_of_the_week_before fdbf(Monday); date d = fdbf.get_date(date(2002,Feb,1)); //2002-Jan-28 Function Overview Function Prototype Description Example days days_until_weekday date, greg_weekday) Calculates the number of days from given date until given weekday. date d(2004,Jun,1); // Tuesday greg_weekday gw(Friday); days_until_weekday(d, gw); // 3 days days days_before_weekday(date, greg_weekday) Calculates the number of day from given date to previous given weekday. date d(2004,Jun,1); // Tuesday greg_weekday gw(Friday); days_before_weekday(d, gw); // 4 days date next_weekday(date, greg_weekday) Generates a date object representing the date of the following weekday from the given date. Can return the given date. date d(2004,Jun,1); // Tuesday greg_weekday gw1(Friday); greg_weekday gw2(Tuesday); next_weekday(d, gw1); // 2004-Jun-4 next_weekday(d, gw2); // 2004-Jun-1 date previous_weekday(date, greg_weekday) Generates a date object representing the date of the previous weekday from the given date. Can return the given date. date d(2004,Jun,1); // Tuesday greg_weekday gw1(Friday); greg_weekday gw2(Tuesday); previous_weekday(d, gw1); // 2004-May-28 previous_weekday(d, gw2); // 2004-Jun-1