[ruby-dev:25508] Fw: DateTime questions [newbie]

まつもと ゆきひろです

[ruby-talk:127729]です。これってバグですか。

---
Date: Sun, 23 Jan 2005 10:03:51 +0900
Posted: Sat, 22 Jan 2005 20:03:46 -0500
From: Navindra Umanee <[e-mail]>
Reply-To: [e-mail]
Subject: DateTime questions [newbie]
To: [e-mail] (ruby-talk ML)
Message-Id: <[e-mail]>
X-ML-Name: ruby-talk
X-Mail-Count: 127729

Hi!

I have some newbie questions.

> DateTime.strptime('2000-09-28 05:23:01 -0400', '%F %T %z').strftime('%s')
=> "970132981"

> DateTime.strptime('970132981', '%s').strftime('%s')
ArgumentError: invalid date
        from /usr/lib/ruby/1.8/date.rb:485:in `new_with_hash'
        from /usr/lib/ruby/1.8/date.rb:495:in `strptime'
        from (irb):31

Why does the first command work but not the second one?  

Out of curiosity is there a standard/builtin way of printing ISO8601
date format instead of having to use to_yaml and chopping off the "---
" garbage string at the beginning of the input or having to manually
specify '%F %T %z'?  

Also, is there a way of printing fractional seconds?  I see that
DateTime has sec_fraction() but '%N' doesn't seem to work in the
string definition.

Thanks a lot!

Cheers,
Navin.