From: Colin Bartlett <colinb2r@...>
Date: 2011-01-01T05:54:33+09:00
Subject: Re: change integer into date

These might help?

Date#jd gives you the Julian Day Number of a date,
and the Julian Day Number of 1970-01-01 (Gregorian) is 2440588,
so you can do things like the following.
There is also the DateTime class, which I have not used until this post.
"Date" also adds Time#to_date and  Time#to_datetime, but I haven't tried those.

IRB in Ruby 1.9.1

require "date"
biaozun = Date.new( 1970, 1, 1 )  #=> #<Date: 1970-01-01 ...>
duration_secs = 1_262_222_200     #=> 1262222200
duration_days_rational = duration_secs.quo( 86400 )  #=> (6311111/432)
duration_days_integer  = duration_secs.div( 86400 )  #=> 14609
duration_days_integer2 = duration_secs / 86400       #=> 14609
date2 = biaozun + duration_days_integer  #=> #<Date: 2009-12-31 ...>
exit
unix_date_zero_jd = biaozun.jd  #=> 2440588

d2jd = date2.jd                        #=> 2455197
dur2_secs = (d2jd - 2440588) * 86400   #=> 1262217600
ut = Time.at( dur2_secs )              #=> 2009-12-31 00:00:00 +0000

dt = DateTime.new( 2010, 12, 31, 13, 42 )
  #=> #<DateTime: 2010-12-31T13:42:00+00:00 ...>

t = dt.to_time      #=> 2010-12-31 13:42:00 +0000
t2 = date2.to_time  #=> 2009-12-31 00:00:00 +0000