adding 1 day to a DATETIME format value

There's more then one way to do this with DateTime which was introduced in PHP 5.2. Unlike using strtotime() this will account for daylight savings time and leap year.

$datetime = new DateTime('2013-01-29');
$datetime->modify('+1 day');
echo $datetime->format('Y-m-d H:i:s');

// Available in PHP 5.3

$datetime = new DateTime('2013-01-29');
$datetime->add(new DateInterval('P1D'));
echo $datetime->format('Y-m-d H:i:s');

// Available in PHP 5.4

echo (new DateTime('2013-01-29'))->add(new DateInterval('P1D'))->format('Y-m-d H:i:s');

// Available in PHP 5.5

$start = new DateTimeImmutable('2013-01-29');
$datetime = $start->modify('+1 day');
echo $datetime->format('Y-m-d H:i:s');

If you want to do this in PHP:

// replace time() with the time stamp you want to add one day to
$startDate = time();
date('Y-m-d H:i:s', strtotime('+1 day', $startDate));

If you want to add the date in MySQL:

-- replace CURRENT_DATE with the date you want to add one day to
SELECT DATE_ADD(CURRENT_DATE, INTERVAL 1 DAY);

The DateTime constructor takes a parameter string time. $time can be different things, it has to respect the datetime format.

There are some valid values as examples :

• 'now' (the default value)
• 2017-10-19
• 2017-10-19 11:59:59
• 2017-10-19 +1day

So, in your case you can use the following.

$dt = new \DateTime('now +1 day'); //Tomorrow
$dt = new \DateTime('2016-01-01 +1 day'); //2016-01-02