How to work with date and time in PHP?

DateTime class provides a nice object oriented interface when working with date and time. It has all the functionality of date functions and more. Therefore use it and have consistency in parts of your code.

$date = DateTime::createFromFormat('Y-m-d', '2015-10-21');
echo $date->format('d.m.Y'); // 21.10.2015

Examples

Difference between dates with DateTime

$start = DateTime::createFromFormat('Y-m-d H:i:s', '2015-10-21 07:28:00');
$arrival = clone $start;
$arrival->add(new DateInterval('P1M6D')); // adds 1 month and 6 days

$diff = $arrival->diff($start);
echo $diff->format('%m month, %d days (total: %a days)'); // 1 month, 6 days (total: 37 days)

Difference between dates with Carbon

Carbon is simple PHP API extension for DateTime. You will find it extremely useful.

echo Carbon::now()->subMinutes(2)->diffForHumans(); // 2 minutes ago

Comparing dates

$now = new DateTime();
$arrival = DateTime::createFromFormat('Y-m-d', '2015-10-21');

if ($now == $arrival) {
    echo "Welcome, Marty McFly!";
} else if ($now < $arrival) {
    echo "Welcome to the future.";
} else {
    echo "Welcome to the past.";
}

Time zone

Default time zone of DateTime::__construct() is the one from the system PHP is currently running on. Good practice to avoid issues later on (when for instance storing them in database and having users from different time zones) is to always specify the UTC time zone:

// Construct a new UTC date
$date = new DateTime('now', new DateTimeZone('UTC'));

// Check current time in different time zones
$date = new DateTime('now', new DateTimeZone('Europe/London'));
echo $date->format('Y-m-d H:i:sP'); // 2015-10 07:28:00+01:00

$date->setTimezone(new DateTimeZone('Pacific/Chatham'));
echo $date->format('Y-m-d H:i:sP'); // 2015-10 07:28:00+13:45

Also don’t forget to set wanted time zone in php.ini files:

date.timezone = "UTC"

Localization

DateTime::format outputs everything only in English. Localization of date and time formats can be done in two ways. With strftime() or IntlDateFormatter which requires intl extension.

Using strftime:

setlocale(LC_TIME, "en_US");
$now = new DateTime('now');
echo strftime("%c", $now->getTimestamp()); // Wed Oct 21 07:28:00 2015

// change locale to Slovenian
setlocale(LC_TIME, "sl_SI");
echo strftime("%c", $now->getTimestamp()); // sre okt 21 07:28:00 2015 CEST

Using IntlDateFormatter:

$now = new DateTime('now');
$fmt = new IntlDateFormatter('en_US', IntlDateFormatter::FULL, IntlDateFormatter::FULL, 'America/New_York', IntlDateFormatter::GREGORIAN);
echo $fmt->format($now); // Wednesday, October 21, 2015 at 07:28:00 AM Eastern Daylight Time

Quirks

Some strange quirks you might want to know and beware when dealing with the following issues.

Zeroed dates

Zeroed dates (0000-00-00, 0000-00-00 00:00:00) can happen in MySQL for example as the default value in columns with DateTime types. If you add zeroed date to DateTime::__construct() they will result in nonsensical date:

$d = new DateTime("0000-00-00");
echo $d->format("Y-m-d"); // "-0001-11-30"

32-bit systems

On 32-bit systems DateTime::getTimestamp() will return false on dates beyond 2038.

DateTimeImmutable

When using setTimezone, setTimestamp, setDate, setTime, modify and some other DateTime methods be careful because they will modify DateTime and return $this. In below example you might expect that two objects below are not the same:

function formatNextMondayFromNow(DateTime $dt) {
    return $dt->modify('next monday')->format('Y-m-d');
}

$d = new DateTime();
echo formatNextMondayFromNow($d); // 2015-10-21
echo $d->format('Y-m-d');         // 2015-10-21

But they are because DateTime is mutable.

For that reason PHP 5.5 introduced DateTimeImmutable class which works the same way as [DateTime] but it never changes itself. Instead it returns a new object.

function formatNextMondayFromNow(DateTimeImmutable $dt) {
    return $dt->modify('next monday')->format('Y-m-d');
}

$d = new DateTimeImmutable();
echo formatNextMondayFromNow($d); // 2015-10-26
echo $d->format('Y-m-d');         // 2015-10-21

See Also

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Content of this work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license. Code snippets in examples are published under the CC0 1.0 Universal (CC0 1.0). Thanks to all the contributors.