PHP 5.6.0beta1 released

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

Descrizione

Stile orientato agli oggetti

public DateTime DateTime::sub ( DateInterval $interval )

Stile procedurale

DateTime date_sub ( DateTime $object , DateInterval $interval )

Subtracts the specified DateInterval object from the specified DateTime object.

Elenco dei parametri

oggetto

Solo per lo stile procedurale: Un oggetto DateTime restituito da date_create(). La funzione modifica questo oggetto.

interval

A DateInterval object

Valori restituiti

Restituisce l'oggetto DateTime per il metodo chaining o FALSE in caso di fallimento.

Esempi

Example #1 DateTime::sub() example

Stile orientato agli oggetti

<?php
$date 
= new DateTime('2000-01-20');
$date->sub(new DateInterval('P10D'));
echo 
$date->format('Y-m-d') . "\n";
?>

Stile procedurale

<?php
$date 
date_create('2000-01-20');
date_sub($datedate_interval_create_from_date_string('10 days'));
echo 
date_format($date'Y-m-d');
?>

I precedenti esempi visualizzeranno:

2000-01-10

Example #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";
?>

Il precedente esempio visualizzerĂ :

2000-01-19 13:59:30
1992-08-15 19:56:58

Example #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";
?>

Il precedente esempio visualizzerĂ :

2001-03-30
2001-03-02

Note

DateTime::modify() is an alternative when using PHP 5.2.

Vedere anche:

add a note add a note

User Contributed Notes 3 notes

up
4
Anonymous
3 years ago
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.)
up
1
itonohito
10 days ago
When trying to pass daylight saving state change time, sub() works incorrectly.

$t = new DateTime( '2014-03-30 02:00:00' );
$t->add( new DateInterval('PT1H') );
echo $->format('Y-m-d H:i:s');

output will be: '2014-03-30 04:00:00'.

 Well, it's ok because at 3:00 a.m. daylight saving time begins in my country, so after  02:59:59 must be 04:00:00.

But if I try to subtract time:

$t = new DateTime( '2014-03-30 04:00:00' );
$t->sub( new DateInterval('PT1H') );
echo $->format('Y-m-d H:i:s');

output will be: '2014-03-30 04:00:00'.

Yes, completely the same, not '2014-03-30 02:00:00' as it should be.
up
0
php at keith tyler dot com
3 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.
To Top