Re: [MacPerl] localtime() behavior question

[Chris Nandor <pudge@pobox.com>]

At 16.09 -0500 1998.12.04, Geoffrey C Kinnel wrote:
>I tried
>
>print scalar (localtime(-1));
>
>on a Unix machine and got 1 second before epoch.
>
>If I try the same on Macperl, I just get the epoch, unmodified.
>
>Is this a known behavior? Can I get dates before Jan 1, 1904 using
>localtime()?

The difference is because Mac OS uses an unsigned 32-bit integer, and so
no, it cannot go back before Jan 1, 1904.  The ranges on Unix are from
-2**31 to 2**31, and for Mac OS are 0 to 2**63.

RedHat Linux, 2.1.129, perl5.004_04:

  % perl -le 'print scalar localtime(-1 - 2**31)'
  Fri Dec 13 15:45:52 1901
  % perl -le 'print scalar localtime(   - 2**31)'
  Fri Dec 13 15:45:52 1901
  % perl -le 'print scalar localtime( 1 - 2**31)'
  Fri Dec 13 15:45:53 1901
  % perl -le 'print scalar localtime(     2**31)'
  Fri Dec 13 15:45:52 1901
  % perl -le 'print scalar localtime(-1 + 2**31)'
  Mon Jan 18 22:14:07 2038


MacPerl 5.2.0r4 PPC, Mac OS 8.5:

  #!perl -l
  print scalar localtime(-1 - 2**0);
  print scalar localtime(   - 2**0);
  print scalar localtime(     2**63);
  print scalar localtime(-1 + 2**63);

Returns:

  Fri Jan  1 00:00:00 1904
  Fri Jan  1 00:00:00 1904
  Mon Feb  6 06:28:15 2040
  Mon Feb  6 06:28:15 2040

--
Chris Nandor          mailto:pudge@pobox.com         http://pudge.net/
%PGPKey = ('B76E72AD', [1024, '0824090B CE73CA10  1FF77F13 8180B6B6'])

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