Comments on: Time 1234567890 is coming up soon

By: Richard Matteson

Richard Matteson — Thu, 12 Feb 2009 21:19:50 +0000

Whoops, I mean GMT -8…

By: Richard Matteson

Richard Matteson — Thu, 12 Feb 2009 21:14:42 +0000

Well, perl is still using a 32 bit signed integer:

$ ## 2147483647 or 0x7fffffff
$ ## local time is PST here (GMT +8)
$ perl -e ‘print scalar localtime(0x7fffffff).”\n”;’
Mon Jan 18 19:14:07 2038
$ perl -e ‘print scalar localtime(0).”\n”;’
Wed Dec 31 16:00:00 1969
$ perl -e ‘print scalar localtime(0x80000000).”\n”;’
Fri Dec 13 12:45:52 1901
$ ## which is the same as -2147483648 (32 bit 2’s complement)
$ perl -e ‘print scalar localtime(-2147483648).”\n”;’
Fri Dec 13 12:45:52 1901

By: Jens Alfke

Jens Alfke — Thu, 12 Feb 2009 16:44:06 +0000

Duh, you’re right of course, and they can’t change that for compatibility reasons. But wasn’t a 64-bit equivalent to that added ages ago?

(It doesn’t affect me because I don’t use POSIX time APIs; I either use Foundation, whose time type is ‘double’, or Java/Ruby/Python/etc. which all use 64-bit ints for time…)

By: fluffy

fluffy — Thu, 12 Feb 2009 16:07:50 +0000

Not true! 0x80000000 is INT_MIN - which is -2^31. The (immediate) problem is that time_t is a signed int, not an unsigned int.

By: Jens Alfke

Jens Alfke — Thu, 12 Feb 2009 16:01:03 +0000

Richard — Not 1901 certainly. The Unix epoch starts at 1/1/1970, so if anything it’d roll over to that…

By: Richard Matteson

Richard Matteson — Thu, 12 Feb 2009 08:05:43 +0000

How about 2147483648 (0x80000000). Will it be
Fri Dec 13 12:45:52 1901 or
Mon Jan 18 19:14:08 2038

By: Jens Alfke

Jens Alfke — Sat, 07 Feb 2009 18:10:32 +0000

Chris — You rock! I’ll be there Friday afternoon with a bottle of champagne. I’ve posted it to del.icio.us.

By: Chris Rowe

Chris Rowe — Sat, 07 Feb 2009 17:45:26 +0000

Check out http://www.coolepochcountdown.com

By: fluffy

fluffy — Thu, 22 Jan 2009 19:45:27 +0000

Bah, wake me up at Sat Nov 27 20:35:28 2032 (0x76543210).

By: Jens Alfke

Jens Alfke — Thu, 22 Jan 2009 19:44:10 +0000

No, timestamps refer to absolute times. Zero is defined as midnight, 1 Jan 1970 GMT. It would be a real mess if you had to store a timezone too, especially because time zones shift around by political whims.