PHP DateTime Timedifference only correct in UTC Timezone?

问题

Can anybody explain me following behaviours:

$end = new DateTime("2015-03-01", new DateTimeZone("Europe/Berlin"));
$start = new DateTime("2015-02-01", new DateTimeZone("Europe/Berlin"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 0 [d] => 28 [h] => 0 [i] => 0 [s] => 0 [invert] => 0 [days] => 28 )

If I don't use a timezone or Europe/Berlin I get wrong time diffs. 28 days is indeed correct, but in this case it's a month.

$end = new DateTime("2015-03-01", new DateTimeZone("UTC"));
$start = new DateTime("2015-02-01", new DateTimeZone("UTC"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 0 [h] => 0 [i] =>; 0 [s] => 0 [invert] => 0 [days] => 28 )

with UTC it works

$end = new DateTime("2015-04-01", new DateTimeZone("Europe/Berlin"));
$start = new DateTime("2015-03-01", new DateTimeZone("Europe/Berlin"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 3 [h] => 0 [i] => 0 [s] => 0 [invert] => 0 [days] => 31 )

1 month and 3 days?!? February, are you spooking here?

$end = new DateTime("2015-04-01", new DateTimeZone("UTC"));
$start = new DateTime("2015-03-01", new DateTimeZone("UTC"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 0 [h] => 0 [i] =>; 0 [s] => 0 [invert] => 0 [days] => 31 )

31 days = 1 month, UTC is correct

$end = new DateTime("2015-05-01", new DateTimeZone("Europe/Berlin"));
$start = new DateTime("2015-04-01", new DateTimeZone("Europe/Berlin"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 0 [d] => 30 [h] => 0 [i] => 0 [s] => 0 [invert] => 0 [days] => 30 )

30 days are for Europe not a month as well?

$end = new DateTime("2015-05-01", new DateTimeZone("UTC"));
$start = new DateTime("2015-04-01", new DateTimeZone("UTC"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 0 [h] => 0 [i] =>; 0 [s] => 0 [invert] => 0 [days] => 30 )

UTC correct

$end = new DateTime("2015-06-01", new DateTimeZone("Europe/Berlin"));
$start = new DateTime("2015-05-01", new DateTimeZone("Europe/Berlin"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 1 [h] => 0 [i] => 0 [s] => 0 [invert] => 0 [days] => 31 )

again 31 days, correct one month, but why +1 day?

$end = new DateTime("2015-06-01", new DateTimeZone("UTC"));
$start = new DateTime("2015-05-01", new DateTimeZone("UTC"));
$diff = $start->diff($end);
//result: DateInterval Object ( [y] => 0 [m] => 1 [d] => 0 [h] => 0 [i] =>; 0 [s] => 0 [invert] => 0 [days] => 31 )

UTC still correct

I don't get it. Thanks for your help.

回答1:

I believe you are experiencing a known bug.

See:

PHP::Bug #52480 Incorrect difference using DateInterval

来源：https://stackoverflow.com/questions/30592498/php-datetime-timedifference-only-correct-in-utc-timezone

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