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## Class template us_dst_rules

boost::date_time::us_dst_rules — Depricated: Class to calculate dst boundaries for US time zones.

## Synopsis

    // In header: <boost/date_time/dst_rules.hpp>

    template<typename date_type_, typename time_duration_type_,
             unsigned int dst_start_offset_minutes = 120,
             short dst_length_minutes = 60>
    class us_dst_rules {
    public:
      // types
      typedef time_duration_type_                             time_duration_type;
      typedef date_type_                                      date_type;
      typedef date_type::year_type                            year_type;
      typedef date_type::calendar_type                        calendar_type;
      typedef date_time::last_kday_of_month< date_type >      lkday;
      typedef date_time::first_kday_of_month< date_type >     fkday;
      typedef date_time::nth_kday_of_month< date_type >       nkday;
      typedef dst_calculator< date_type, time_duration_type > dstcalc;

      // public static functions
      static time_is_dst_result
      local_is_dst(const date_type &, const time_duration_type &) ;
      static bool is_dst_boundary_day(date_type) ;
      static date_type local_dst_start_day(year_type) ;
      static date_type local_dst_end_day(year_type) ;
      static time_duration_type dst_offset() ;
    };

## Description

### `us_dst_rules` public static functions

1.     static time_is_dst_result
       local_is_dst(const date_type & d, const time_duration_type & td) ;

   Calculates if the given local time is dst or not.

   Determines if the time is really in DST or not. Also checks for invalid and ambiguous.

2.     static bool is_dst_boundary_day(date_type d) ;

3.     static date_type local_dst_start_day(year_type year) ;

4.     static date_type local_dst_end_day(year_type year) ;

5.     static time_duration_type dst_offset() ;