Ruby in a Nutshell

Name

Date — Date class

Synopsis

Date is a class to represent the calendar date. Date is based on the Julian day number, which is the number of days since midday, January 1st 4713 BC.

Currently we use the Gregorian calendar, but the Julian calendar was used prior to that time (before 1752 in England, for example). The calendar shift date is different in each country. Date class can handle both calendars and arbitrary shift dates.

There’s no relation between Julian day number and Julian calendar; it’s just coincidence.

Required Library

require 'date'

Example

require 'date'

# 3000 days after Ruby was born
puts Date::new(1993,2,24)+3000, "\n"  # 2001-05-13

Included Module

Comparable

Class Methods

Date::exist?(year, month, day[, start])

Date::exist3?(year, month, day[, start])

Returns the Julian day number corresponding to the specified year, month, and day of year, if they are correct. If they aren’t correct, returns nil.

Date::exist2?(year, yday[, start])

Returns the Julian day number corresponding to the specified year and day of year, if they are correct. If they aren’t correct, returns nil.

Date::existw?(year, week, wday[, start])

Returns the Julian day number corresponding to the specified calendar week-based year, calendar week, and calendar weekday, if they are correct. If they aren’t correct, returns nil.

Date::new(year, month, day[, start])

Date::new3(year, month, day[, start])

Creates a Date object corresponding to the specified year, month, and day of the month.

Date::new1(jd[, start