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
Beschreibung
Objektorientierter Stil
Prozeduraler Stil
Subtracts the specified DateInterval object from the specified DateTime object.
Parameter-Liste
-
object -
Nur bei prozeduralem Aufruf: Ein von date_create() zurückgegebenes DateTime-Objekt. Diese Funktion verändert dieses Objekt.
-
interval -
A DateInterval object
Rückgabewerte
Gibt das DateTime-Objekt
für die Verkettung von Methoden zurück Im Fehlerfall wird FALSE zurückgegeben.
Beispiele
Beispiel #1 DateTime::sub() example
Objektorientierter Stil
<?php
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('P10D'));
echo $date->format('Y-m-d') . "\n";
?>
Prozeduraler Stil
<?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');
?>
Die obigen Bespiele erzeugen folgende Ausgabe:
2000-01-10
Beispiel #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";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
2000-01-19 13:59:30 1992-08-15 19:56:58
Beispiel #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";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
2001-03-30 2001-03-02
Anmerkungen
DateTime::modify() is an alternative when using PHP 5.2.
Siehe auch
- 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.