PHP Manual: Alters the timestamp

Description

Object-oriented style

public DateTimefalse DateTime::modify(string $modifier)

Procedural style

DateTimefalse date_modify(DateTime $object, string $modifier)

Alter the timestamp of a DateTime object by incrementing or decrementing in a format accepted by DateTimeImmutable::__construct.

Parameters

object: Procedural style only: A DateTime object returned by date_create. The function modifies this object.
modifier: A date/time string. Valid formats are explained in Date and Time Formats.

Return Values

Returns the modified DateTime object for method chaining or false on failure.

Errors/Exceptions

Object Orientated API only: If an invalid Date/Time string is passed, DateMalformedStringException is thrown.

Changelog

Version	Description
8.3.0	Now throws DateMalformedStringException with DateTime::modify if an invalid string is passed, instead of a warning. date_modify has not been changed.

Examples

Example #1 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

Example #2 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

Example #3 All formats of Date and Time are supported

<?php
$date = new DateTime('2020-12-31');

$date->modify('July 1st, 2023');
echo $date->format('Y-m-d H:i') . "\n";

$date->modify('Monday next week');
echo $date->format('Y-m-d H:i') . "\n";

$date->modify('17:30');
echo $date->format('Y-m-d H:i') . "\n";
?>