为什么perl的本地时间似乎输出错误的月份？ [英] Why does perl's localtime seem to output the wrong month?

问题描述

我已经看到其他答案，但是由于某些原因他们并不适合我。

I've seen other answers, but they're not working for me for some reason.

我试图用Perl脚本中的日期以下代码。

I'm trying to get yesterday's date in a Perl script using the following code.

为了将来参考，今天的日期是2015年11月12日

For future reference, today's date is November 12, 2015

my (undef, undef, undef, $mday,$mon,$year) = localtime();
my $prev_day = timelocal(0, 0, 0, $mday-1, $mon, $year);
(undef, undef, undef, $mday,$mon,$year) = localtime($prev_day);
$year += 1900;

print "Yesterday's Day: $mday, Month: $mon, Year: $year\n";

除了我的输出看起来像这样

Except my output looks like this

Yesterday's Day: 11, Month: 10, Year: 2015.

我应该阅读昨天的日期为 Day：11，Month：11，Year：2015 。为什么要扣除这个月份？

I should be reading yesterday's date as Day: 11, Month: 11, Year: 2015. Why is the month being subtracted?

编辑：这不同于建议的答案，因为我想知道为什么当地时间似乎写错了一个月。 >

This is different than the suggested answer because I'm wondering why local time seems to be writing the wrong month.

推荐答案

localtime 的文档说这个

The documentation for localtime says this

$ mday是月份和月份月份在0..11范围内，0表示1月和11表示12月。

$mday is the day of the month and $mon the month in the range 0..11, with 0 indicating January and 11 indicating December.

所以要得到一个月的数字为1，您需要 $ mon + 1 ，或者您只需将一个添加到 $ mday 在你添加1900到$ code> $ year的同一时间

So to get a month number with 1 for January you need $mon+1, or you can just add one to $mday at the same time as you add 1900 to $year

像这样

use strict;
use warnings 'all';

use Time::Local;

my ($y, $m, $d) = (localtime)[5,4,3];

my $yesterday = timelocal(0, 0, 0, $d-1, $m, $y);
($y, $m, $d) = (localtime($yesterday))[5,4,3];
$y += 1900;
++$m;

print "Yesterday's Day: $d, Month: $m, Year: $y\n";

输出

output

Yesterday's Day: 11, Month: 11, Year: 2015

更好的方法是使用核心库 Time :: Piece 像这样

A better way is to use the core library Time::Piece like this

use strict;
use warnings 'all';

use Time::Piece;
use Time::Seconds 'ONE_DAY';

my $yesterday = localtime() - ONE_DAY;

printf "Yesterday's Day: %d, Month: %d, Year: %d\n",
    $yesterday->mday,
    $yesterday->mon,
    $yesterday->year;

输出

output

Yesterday's Day: 11, Month: 11, Year: 2015

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