"DateTime-> modify('+ 0 days')"修改DateTime对象

Question

任何人都可以详细说明为什么下面的DateTime->modify()代码产生那些奇怪的矛盾结果,取决于PHP版本(它是一个错误？在哪个PHP版本？).

我希望所有的例子都能生成创建对象的相同日期和时间,但显然并非如此.

唯一可行的例子是中间的那个,DateTime从UNIX时间戳创建对象,然后设置时区(它不能在构造时设置,因为它将被忽略).

PHP 5.4.4和5.4.6:

FROM TIMESTAMP, NO TZ:
2012-08-21 22:00:00 GMT+0000 (offset 0)  <-- different 
2012-08-21 23:00:00 GMT+0000 (offset 0)  <-- from this
FROM TIMESTAMP, WITH TZ:
2012-08-22 00:00:00 CEST (offset 7200)
2012-08-22 00:00:00 CEST (offset 7200)
FROM STRING:
2012-08-22 00:00:00 CEST (offset 7200)
2012-08-22 00:00:00 CEST (offset 7200)

PHP 5.2.0:

FROM TIMESTAMP, NO TZ:
2012-08-21 22:00:00 GMT+0100 (offset 7200)
2012-08-21 22:00:00 GMT+0100 (offset 7200)
FROM TIMESTAMP, WITH TZ:
2012-08-22 00:00:00 CEST (offset 7200)
2012-08-22 00:00:00 CEST (offset 7200)
FROM STRING:
2012-08-22 00:00:00 CEST (offset 7200)  <-- different
2012-08-21 23:00:00 CEST (offset 7200)  <-- from this

码:

<?php
  $tz = new DateTimeZone('Europe/Berlin');

  echo "FROM TIMESTAMP, NO TZ:\n";

  $date = new DateTime('@'.strtotime('2012-08-22 00:00:00 CEST'));
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";

  $date->modify('+0 days');
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";

  echo "FROM TIMESTAMP, WITH TZ:\n";

  $date = new DateTime('@'.strtotime('2012-08-22 00:00:00 CEST'));
  $date->setTimezone($tz);
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";

  $date->modify('+0 days');
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";

  echo "FROM STRING:\n";

  $date = new DateTime('2012-08-22 00:00:00 CEST', $tz);
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";

  $date->modify('+0 days');
  echo $date->format('Y-m-d H:i:s T').' (offset '.$date->getOffset().")\n";
?>

Answer 1

使用DateTime::add()和指定适当的DateInterval "P0D"日期不会更改日期。我认为这是 PHP 中的一个错误，请善意地报告它。