From: Tanaka Akira Date: 2012-07-11T14:06:01+09:00 Subject: [ruby-core:46319] Re: [ruby-trunk - Feature #6720][Open] Discrepancy between DateTime#strftime('%s') and Time#strftime('%s') before 1582-10-15 2012/7/11 phasis68 (Heesob Park) : > > I found some discrepancy between DateTime#strftime('%s') and Time#strftime('%s') on date before 1582-10-15 This is not a bug. The difference is caused because Time uses Proleptic Gregorian calendar (doc/NEWS-1.9.2) but DateTime uses Julian/Gregorian calendar at Italy by default. I guess you can use DateTime with Proleptic Gregorian calendar (doc/NEWS-1.9.3). -- Tanaka Akira