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Converting Between Time Zones
CodeExpectedActual
now = Time.now
 Sat Mar 18 20:15:58 EST 2006 Mon Mar 27 16:43:32 EST 2006 
now = now.gmtime
 Sun Mar 19 01:15:58 UTC 2006 Mon Mar 27 21:43:32 UTC 2006 
now = now.localtime
 Sat Mar 18 20:15:58 EST 2006 Mon Mar 27 16:43:32 EST 2006 
require 'date'
local = DateTime.now
local.to_s
 "2006-03-18T20:15:58-0500" "2006-03-27T16:43:32-0500" 
utc = local.new_offset(0)
utc.to_s
 "2006-03-19T01:15:58Z" "2006-03-27T21:43:32Z" 
local = DateTime.now
utc = local.new_offset
local.offset
 Rational(-5, 24) Rational(-5, 24) 
local_from_utc = utc.new_offset(local.offset)
local_from_utc.to_s
 "2006-03-18T20:15:58-0500" "2006-03-27T16:43:32-0500" 
local == local_from_utc
 true true 
#Convert local (Eastern) time to Pacific time
eastern = DateTime.now
eastern.to_s
 "2006-03-18T20:15:58-0500" "2006-03-27T16:43:32-0500" 
pacific_offset = Rational(-7, 24)
pacific = eastern.new_offset(pacific_offset)
pacific.to_s
 "2006-03-18T18:15:58-0700" "2006-03-27T14:43:32-0700" 
class Time
  def convert_zone(to_zone)
    original_zone = ENV["TZ"]
    utc_time = dup.gmtime
    ENV["TZ"] = to_zone
    to_zone_time = utc_time.localtime
    ENV["TZ"] = original_zone
    return to_zone_time
  end
end
t = Time.at(1000000000)
 Sat Sep 08 21:46:40 EDT 2001 Sat Sep 08 21:46:40 EDT 2001 
t.convert_zone("US/Pacific")
 Sat Sep 08 18:46:40 PDT 2001 Sat Sep 08 18:46:40 PDT 2001 
t.convert_zone("US/Alaska")
 Sat Sep 08 17:46:40 AKDT 2001 Sat Sep 08 17:46:40 AKDT 2001 
t.convert_zone("UTC")
 Sun Sep 09 01:46:40 UTC 2001 Sun Sep 09 01:46:40 UTC 2001 
t.convert_zone("Turkey")
 Sun Sep 09 04:46:40 EEST 2001 Sun Sep 09 04:46:40 EEST 2001 
t.convert_zone("Asia/Calcutta")
 Sun Sep 09 07:16:40 IST 2001 Sun Sep 09 07:16:40 IST 2001 
ENV["TZ"] = "Africa/Lagos"
t = Time.at(1000000000)
 Sun Sep 09 02:46:40 WAT 2001 Sun Sep 09 02:46:40 WAT 2001 
ENV["TZ"] = nil
t.convert_zone("Singapore")
 Sun Sep 09 09:46:40 SGT 2001 Sun Sep 09 09:46:40 SGT 2001 
t.convert_zone("US/Eastern")
 Sat Sep 08 21:46:40 EDT 2001 Sat Sep 08 21:46:40 EDT 2001