PHP DateTime->diff() 无法正常工作

Question

我遇到了一个有趣的案例，与DateTime类的diff()方法有关。

如果我尝试计算两个日期之间的差异，例如

$datetime1 = new \DateTime('June 2019');
$datetime2 = new \DateTime('July 2019');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%m');

，结果我得到0。

为什么会这样？

Print_r 的：

$datetime1:

DateTime Object ( [date] => 2019-06-01 00:00:00.000000 
[timezone_type] => 3 [timezone] => Europe/Berlin )

$datetime2:

DateTime Object ( [date] => 2019-07-01 00:00:00.000000 
[timezone_type] => 3 [timezone] => Europe/Berlin )

$间隔：

DateInterval Object ( [y] => 0 [m] => 0 [d] => 30 [h] => 0 [i] => 0 [s] => 0 [f] => 0 
[weekday] => 0 [weekday_behavior] => 0 [first_last_day_of] => 0 
[invert] => 0 [days] => 30 [special_type] => 0 [special_amount] => 0
 [have_weekday_relative] => 0 [have_special_relative] => 0 )

Answer 1

PHP 中的时区和日期处理存在很大的不一致

这似乎是一个错误（就日期时间格式被强制为 GMT* 偏移量而言，according to this comment）。

*（但强制到 GMT 似乎与下面代码建立的结果不一致）

将服务器时区值设置为任何时区都不会影响此脚本时区异常。

以下两个案例展示了不同时区发生的情况：

---

案例一：

以下代码将输出每个时区的结果列表：

$tzList = DateTimeZone::listIdentifiers(DateTimeZone::ALL);

print "Current Zone:". print_r(ini_get('date.timezone'),true)."<br>\n<BR>\n";

foreach($tzList as $tzRow) {
    $tz = new DateTimeZone($tzRow);
    //$tz = null;
    $datetime1 = new \DateTime('June 2019', $tz);
    $datetime2 = new \DateTime('July 2019', $tz);
    $interval = $datetime1->diff($datetime2, false);
    echo $interval->format('%a %m') . PHP_EOL. " :: ";

    print print_r($datetime1->getTimezone(),true)."<BR>";
}

此列表输出的结果显示0 和1 月的其余部分的比率很高（~60%）。

请看这里：http://sandbox.onlinephpfunctions.com/code/b18ba13deb94d112b12630a12265363fb6c7670b

---

案例2：

在创建对象后设置时区，得到一致的答案（尽管不正确）

$tzList = DateTimeZone::listIdentifiers(DateTimeZone::ALL);

print "Current Zone:". print_r(ini_get('date.timezone'),true)."<br>\n<BR>\n";

foreach($tzList as $tzRow) {
    //$tz = new DateTimeZone($tzRow);
    $tz = null;
    $datetime1 = new \DateTime('June 2019', $tz);
    $datetime2 = new \DateTime('July 2019', $tz);
    $datetime1->setTimezone(new DateTimeZone($tzRow));
    $datetime2->setTimezone(new DateTimeZone($tzRow));
    $interval = $datetime1->diff($datetime2, false);
    echo $interval->format('%a %m') . PHP_EOL. " :: ";

    print print_r($datetime1->getTimezone(),true)."<BR>";
}
 

此输出在此处生成所有所有 30 天；但所有相差 0 个月。

在此处查看代码：http://sandbox.onlinephpfunctions.com/code/7bcc62f4e36f41df71b9cb928de75a53f233d9fd

---

因此，如果您想使用有时正确的结果或普遍不正确但一致的结果，您可以选择通过设置 when 在 DateTime 对象中建立 Timezone 值。

---

可能的解决方案：

如果服务器时区正确设置为 UTC“正确”时区（在Case 1 中自然返回“1”月，则上述 CASE 2 在指定给 DateTime 的所有时区中始终有效对象。

Answer 2

问题出在您的时区。

有一个帖子解释了它here。

看这个例子：

<?php

echo "----- Europe/Berlin -----\n";
date_default_timezone_set('Europe/Berlin'); 
$datetime1 = new \DateTime('June 2019');
$datetime2 = new \DateTime('July 2019');
print_r($datetime1);
print_r($datetime2);

$interval = $datetime1->diff($datetime2);
print_r($interval);

echo "%m = " . $interval->format('%m') . PHP_EOL;
echo "%a = " . $interval->format('%a') . PHP_EOL;
echo "%s = " . $interval->format('%s') . PHP_EOL;


echo "\n\n\n----- America/Sao_Paulo -----\n";
date_default_timezone_set('America/Sao_Paulo'); 
$datetime1 = new \DateTime('June 2019');
$datetime2 = new \DateTime('July 2019');
print_r($datetime1);
print_r($datetime2);

$interval = $datetime1->diff($datetime2);
print_r($interval);

echo "%m = " . $interval->format('%m') . PHP_EOL;
echo "%a = " . $interval->format('%a') . PHP_EOL;
echo "%s = " . $interval->format('%s') . PHP_EOL;

还有输出：

$ php date_diff.php 
----- Europe/Berlin -----
DateTime Object
(
    [date] => 2019-06-01 00:00:00.000000
    [timezone_type] => 3
    [timezone] => Europe/Berlin
)
DateTime Object
(
    [date] => 2019-07-01 00:00:00.000000
    [timezone_type] => 3
    [timezone] => Europe/Berlin
)
DateInterval Object
(
    [y] => 0
    [m] => 0
    [d] => 30
    [h] => 0
    [i] => 0
    [s] => 0
    [f] => 0
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 30
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)
%m = 0
%a = 30
%s = 0



----- America/Sao_Paulo -----
DateTime Object
(
    [date] => 2019-06-01 00:00:00.000000
    [timezone_type] => 3
    [timezone] => America/Sao_Paulo
)
DateTime Object
(
    [date] => 2019-07-01 00:00:00.000000
    [timezone_type] => 3
    [timezone] => America/Sao_Paulo
)
DateInterval Object
(
    [y] => 0
    [m] => 1
    [d] => 0
    [h] => 0
    [i] => 0
    [s] => 0
    [f] => 0
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 30
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)
%m = 1
%a = 30
%s = 0

在我的时区$interval->format('%m'); 是 1。

您可以在日期上设置时区以计算它们之间的差异。

$datetime1 = new \DateTime('June 2019', new DateTimeZone('UTC'));
$datetime2 = new \DateTime('July 2019', new DateTimeZone('UTC'));
$interval = $datetime1->diff($datetime2);
print_r($interval);
echo "%m = " . $interval->format('%m') . PHP_EOL;

$ php date_diff.php 
DateInterval Object
(
    [y] => 0
    [m] => 1
    [d] => 0
    [h] => 0
    [i] => 0
    [s] => 0
    [f] => 0
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 30
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)
%m = 1

Answer 3

您可以通过添加时区来尝试吗？

$timezones = [
    'UTC',
    'Europe/Berlin',
    'America/Belize',
    'Asia/Hong_Kong',
];

foreach ($timezones as $timezone) {
    $tz = new DateTimeZone($timezone);
    $datetime1 = new \DateTime('June 2019', $tz);
    $datetime2 = new \DateTime('July 2019', $tz);
    $interval = $datetime1->diff($datetime2);
    echo str_pad($timezone, 20, ' ').' '.$interval->format('months: %M,  day: %D,  days: %a') . PHP_EOL;
}

结果：

UTC                  months: 01,  day: 00,  days: 30
Europe/Berlin        months: 00,  day: 30,  days: 30
America/Belize       months: 01,  day: 00,  days: 30
Asia/Hong_Kong       months: 00,  day: 30,  days: 30