DateTime::setTimezone
Note that the sub() and add() methods will modify the value of the object you're calling the method on! This is very untypical for a method that returns a value of its own type. You could misunderstand it that the method would return a new instance with the modified value, but in fact it modifies itself! This is undocumented here. (Only a side note on procedural style mentions it, but it obviously does not apply to object oriented style.)
DateTime::sub
date_sub
(PHP 5 >= 5.3.0)
DateTime::sub -- date_sub — Subtracts an amount of days, months, years, hours, minutes and seconds from a DateTime object
Opis
Styl obiektowy
Styl proceduralny
Subtracts the specified DateInterval object from the specified DateTime object.
Parametry
-
object -
Tylko styl proceduralny: Obiekt DateTime zwracany przez date_create(). Funkcja modyfikuje ten obiekt.
-
interval -
A DateInterval object
Zwracane wartości
Zwraca zmodyfikowany obiekt DateTime lub FALSE w przypadku niepowodzenia.
Przykłady
Przykład #1 DateTime::sub() example
Styl obiektowy
<?php
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('P10D'));
echo $date->format('Y-m-d') . "\n";
?>
Styl proceduralny
<?php
$date = date_create('2000-01-20');
date_sub($date, date_interval_create_from_date_string('10 days'));
echo date_format($date, 'Y-m-d');
?>
Powyższe przykłady wyświetlą:
2000-01-10
Przykład #2 Further DateTime::sub() examples
<?php
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('PT10H30S'));
echo $date->format('Y-m-d H:i:s') . "\n";
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('P7Y5M4DT4H3M2S'));
echo $date->format('Y-m-d H:i:s') . "\n";
?>
Powyższy przykład wyświetli:
2000-01-19 13:59:30 1992-08-15 19:56:58
Przykład #3 Beware when subtracting months
<?php
$date = new DateTime('2001-04-30');
$interval = new DateInterval('P1M');
$date->sub($interval);
echo $date->format('Y-m-d') . "\n";
$date->sub($interval);
echo $date->format('Y-m-d') . "\n";
?>
Powyższy przykład wyświetli:
2001-03-30 2001-03-02
Notatki
DateTime::modify() is an alternative when using PHP 5.2.
Zobacz też:
- DateTime::add() - Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object
- DateTime::diff() - Returns the difference between two DateTime objects
- DateTime::modify() - Alters the timestamp
add a note
User Contributed Notes
DateTime::sub - [2 notes]
Anonymous ¶
2 years ago
php at keith tyler dot com ¶
2 years ago
If you use diff() after sub(), the effects of the sub() will be repeated on the date object.
It doesn't matter if the object is the one diffed or doing the diffing (i.e. which object you call diff() from).
<?php
$today = new DateTime();
$newdate = new DateTime();
print_r($newdate);
$newdate->sub(new DateInterval("PT1S"));
print_r($newdate);
$s = $newdate->diff($today);
print_r($newdate);
$s = $today->diff($newdate);
print_r($newdate);
$s = $today->diff($newdate);
print_r($newdate);
?>
Prints:
DateTime Object
(
[date] => 2010-11-30 18:43:48
[timezone_type] => 3
[timezone] => America/Los_Angeles
)
DateTime Object
(
[date] => 2010-11-30 18:43:47
[timezone_type] => 3
[timezone] => America/Los_Angeles
)
DateTime Object
(
[date] => 2010-11-30 18:43:46
[timezone_type] => 3
[timezone] => America/Los_Angeles
)
DateTime Object
(
[date] => 2010-11-30 18:43:45
[timezone_type] => 3
[timezone] => America/Los_Angeles
)
DateTime Object
(
[date] => 2010-11-30 18:43:44
[timezone_type] => 3
[timezone] => America/Los_Angeles
)
Note that using add() instead of sub() does NOT have the same effect.
This is particularly undesirable -- in this example you make a datetime, use sub() to make it a relative time in the past, and then date->diff() to confirm the difference. But the diff() inadvertendly makes the difference 2x.