Perl函数localtime在1964年到1967年间给出了不正确的值

我从Perl中的localtime函数中得到了一些奇怪的值。下面是一些我得到不正确值的代码

特别是，此代码用于确定每年第一个工作日

#!/usr/bin/perl
use strict 'vars';
use Time::Local;
use POSIX qw(strftime);

mytable();

sub mytable {
   print "Year" . " "x4 .  "Jan 1st (localtime)" . " "x4 . "Jan 1st (Gauss)\n";
   foreach my $year ( 1964 .. 2017 )
     {
       my $janlocaltime = evalweekday( 1,1,$year);
       my $jangauss     = gauss($year);
       my $diff = $jangauss - $janlocaltime;
       printf "%4s%10s%-12s ",$year,"",$janlocaltime;
       printf "%12s",$jangauss;
       printf " <----- ERROR: off by %2s", $diff if ( $diff != 0 );
     print "\n";
     }
}

sub evalweekday {
   ## Using "localtime"
   my ($day,$month,$year) = @_;
   my $epoch   =  timelocal(0,0,0, $day,$month-1,$year-1900);
   my $weekday = ( localtime($epoch) ) [6];
   return $weekday;
 }

sub gauss {
   ## Alternative approach
   my ($year) = @_;
   my $weekday =
     (  1 + 5 * ( ( $year - 1 ) % 4 )
      + 4 * ( ( $year - 1 ) % 100 )
      + 6 * ( ( $year - 1 ) % 400 )
    ) % 7;
   return $weekday;
 }

我不确定它是否相关，但我的操作系统是macOS Sierra版本10.12.3

我已经通读了文档，但是我没有看到关于1968年之前返回的值的任何内容（或者说我是瞎的）。我也尝试过做一个网络搜索，但除了对数组值和一年中的月数和日数的典型误解之外，我没有找到任何东西

---

有人能帮我解释一下我的错误吗？或者，如果这是我的Perl版本的一个问题，请告诉我可以做些什么来解决它。

这可能与Time:：Local中负历元值的处理方式有关。看看

在我的Linux机器（Perl5.20）上，您的代码很好地演示了这个问题。如果打印出收到的历元值，您将看到问题，即

timelocal

返回的历元变大，而不是变负：

Year       Epoch Jan 1st (localtime)     Jan 1st (Gauss)
1964  2966342400 2                       3 <----- ERROR: off by  1
1965  2997964800 4                       5 <----- ERROR: off by  1
1966  3029500800 5                       6 <----- ERROR: off by  1
1967  3061036800 6                       0 <----- ERROR: off by -6
1968   -63185400 1                       1
1969   -31563000 3                       3
1970      -27000 4                       4
1971    31509000 5                       5
1972    63045000 6                       6

---

6=Saturday

与Wikipedian视图相匹配：

我删除了函数调用前面的

&

，因为这些不再是必需的（至少在过去10年中）。

This is perl 5, version 18, subversion 2 (v5.18.2) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)

Copyright 1987-2013, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
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Year       Epoch Jan 1st (localtime)     Jan 1st (Gauss)
1964  2966342400 2                       3 <----- ERROR: off by  1
1965  2997964800 4                       5 <----- ERROR: off by  1
1966  3029500800 5                       6 <----- ERROR: off by  1
1967  3061036800 6                       0 <----- ERROR: off by -6
1968   -63185400 1                       1
1969   -31563000 3                       3
1970      -27000 4                       4
1971    31509000 5                       5
1972    63045000 6                       6

use DateTime;
my $dt = DateTime->new(
    year   => 1966, # Real Year
    day    => 1,    # 1-31
    month  => 1,    # 1-12
    hour   => 0,    # 0-23
    second => 0,    # 0-59
);
print $dt->dow . "\n";

6