CodeCogs

Calenders: Gregorian, Julian and Excel

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Interface

#include <codecogs/units/date/constants.h>

using namespace Units::Date;

enum dateDiffType
enum weekNumStd
enum weekdays
enum months

Overview

Mode	Description
cal_Julian	The Julian calendar was introduced in 45BC and was commonly used until the late 16 century. The Julian calendar is 365 1/4 days long, which gives an error of 1 day in every 128 years.
cal_Gregorian	The Gregorian calendar was first introduced in 1582 by predominantly Catholic countries, to rectify the error in the Julian calendar. This change occurred on the 4th October 1582, with 10 days being lost, such that 15th October was the next day. Over the next 500 years, the majority of the world has adopted this standard, the main exceptions being the Greek and Russian Orthodox churches, which still use the Julian calendar.
cal_Excel	The Excel date system isn't an official date system, but we use it here to provide compatibility to Microsoft Excel referring to a system that starts on 1 Jan 1900, such that years values below 1900, are assumed to be 1900+year. e.g. 20 is 1920; 110 is 2010. Excel on the Mac doesn't allow value prior to 1 January 1904, however for all practical purposes this limitation can be ignored. Aside from this peculiarity, both Excel date systems are identical to the Gregorian system.

ENUM

dateDiffType

Type	Description
dd_Europe	Start or end dates that occur on the 31st of a month become equal to the 30th of the same month.
dd_USA	This is identical to the \e European system with one exception that applies only to end dates: If the end date occurs on the 31st of a month it is moved to the 1st of the next month \b if the start date is earlier than the 30th. This method is sometime also called the 'NASD' method.

ENUM

weekNumStd

Standard	Description
wkn_Simple	The simple week numbering scheme: - week 1 starts on the 1st January of any given year - week n+1 starts 7 days after week n
wkn_Excel	The Microsoft Excel numbering scheme: - week 1 starts on the 1st January of any given year - weeks also start on a Monday (resulting in short week 1's)
wkn_ISO	The ISO8601 standard that defines a week number as: - weeks start on a Monday. - week 1 of a given year is the one that includes the first Thursday of that year or (equivalently) the week that includes January 4th.

ENUM

weekdays

ENUM

months