From: Ben Giddings <bg-rubytalk@...>
Date: 2009-09-19T15:22:41+09:00
Subject: Re: Time.new.utc Question

On Sep 18, 2009, at 23:04, Dan Fitzpatrick wrote:
> Why is the time printed 6 hours apart but in unix time it is 7 hours  
> apart? Is it a DST issue?

To me, this seems like a bug in strftime.  The only difference between  
'local' and 'utc' should be in the default time zone shown.   
Internally they're both the same time.  local.to_i and utc.to_i should  
be the same number.

It seems to me that, from the description, Time#to_i and  
Time#strftime("%s").to_i should be the same number, but they're  
apparently not.

My guess about what's happening is that internally Ruby creates a  
struct_tm object by using Time#to_a, which would be different for the  
two different variables since it uses the display values for the  
hours, minutes, seconds, etc.  It then uses those fields in a call to  
the underlying C strftime() call. Since the only time-zone related  
field in a struct_tm is tm_isdst, the time-zone related info is mostly  
lost.

I'd recommend that if you want the epoch time, just use Time#to_i and  
not Time#strftime("%s").to_i

Ben