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## Class template gregorian_calendar_base

boost::date_time::gregorian_calendar_base — An implementation of the Gregorian calendar.

## Synopsis

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

    template<typename ymd_type_, typename date_int_type_>
    class gregorian_calendar_base {
    public:
      // types
      typedef ymd_type_            ymd_type;       // define a type a date split into components
      typedef ymd_type::month_type month_type;     // define a type for representing months
      typedef ymd_type::day_type   day_type;       // define a type for representing days
      typedef ymd_type::year_type  year_type;      // Type to hold a stand alone year value (eg: 2002).
      typedef date_int_type_       date_int_type;  // Define the integer type to use for internal calculations.

      // public static functions
      static unsigned short day_of_week(const ymd_type &) ;
      static int week_number(const ymd_type &) ;
      static date_int_type day_number(const ymd_type &) ;
      static date_int_type julian_day_number(const ymd_type &) ;
      static long modjulian_day_number(const ymd_type &) ;
      static ymd_type from_day_number(date_int_type) ;
      static ymd_type from_julian_day_number(date_int_type) ;
      static ymd_type from_modjulian_day_number(long) ;
      static bool is_leap_year(year_type) ;
      static unsigned short end_of_month_day(year_type, month_type) ;
      static ymd_type epoch() ;
      static unsigned short days_in_week() ;
    };

## Description

This is a parameterized implementation of a proleptic Gregorian Calendar that can be used in the creation of date systems or just to perform calculations. All the methods of this class are static functions, so the intent is to never create instances of this class.

### `gregorian_calendar_base` public static functions

1.     static unsigned short day_of_week(const ymd_type & ymd) ;

2.     static int week_number(const ymd_type & ymd) ;

3.     static date_int_type day_number(const ymd_type & ymd) ;

4.     static date_int_type julian_day_number(const ymd_type & ymd) ;

5.     static long modjulian_day_number(const ymd_type & ymd) ;

6.     static ymd_type from_day_number(date_int_type) ;

7.     static ymd_type from_julian_day_number(date_int_type) ;

8.     static ymd_type from_modjulian_day_number(long) ;

9.     static bool is_leap_year(year_type) ;

10.     static unsigned short end_of_month_day(year_type y, month_type m) ;

11.     static ymd_type epoch() ;

12.     static unsigned short days_in_week() ;