DateTime::modify

(PHP 5 >= 5.2.0, PHP 7)

Alters the timestamp

public DateTime DateTime::modify ( string $modify )

Object oriented style

Procedural style

DateTime date_modify ( DateTime $object , string $modify )

Alter the timestamp of a DateTime object by incrementing or decrementing in a format accepted by strtotime().

Parameters:

object

Procedural style only: A DateTime object returned by date_create(). The function modifies this object.

modify

A date/time string. Valid formats are explained in Date and Time Formats.

Returns:

Returns the DateTime object for method chaining or FALSE on failure.

Changelog:

5.3.6

Absolute date/time statements now take effect. Previously, only relative parts were used.

5.3.0

Changed the return value on success from NULL to DateTime.

Examples:

DateTime::modify() example

Object oriented style

<?php
$date = new DateTime('2006-12-12');
$date->modify('+1 day');
echo $date->format('Y-m-d');
?>

Procedural style

<?php
$date = date_create('2006-12-12');
date_modify($date, '+1 day');
echo date_format($date, 'Y-m-d');
?>

The above examples will output:

2006-12-13

Beware when adding or subtracting months

<?php
$date = new DateTime('2000-12-31');

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";
?>

The above example will output:

2001-01-31
2001-03-03