how do I subtract 24 hour from date time object in PHP

Question

I have the following code:

  $now = date(\"Y-m-d H:m:s\");
  $date = date(\"Y-m-d H:m:s\", strtotime(\'-24 hours\', $now));

However, now it

Answer 1

strtotime() expects a unix timestamp (which is number seconds since Jan 01 1970)

$date = date("Y-m-d H:i:s", strtotime('-24 hours', time())); ////time() is default so you do not need to specify.

i would suggest using the datetime library though, since it's a more object oriented approach.

$date = new DateTime(); //date & time of right now. (Like time())
$date->sub(new DateInterval('P1D')); //subtract period of 1 day

The advantage of this is that you can reuse the DateInterval:

$date = new DateTime(); //date & time of right now. (Like time())
$oneDayPeriod = new DateInterval('P1D'); //period of 1 day
$date->sub($oneDayPeriod);
$date->sub($oneDayPeriod); //2 days are subtracted.
$date2 = new DateTime(); 
$date2->sub($oneDayPeriod); //can use the same period, multiple times.

Carbon (update 2020)

Most popular library for processing DateTimes in PHP is Carbon.

Here you would simply do:

$yesterday = Carbon::now()->subDay();

Answer 2

$date = (new \DateTime())->modify('-24 hours');

or

$date = (new \DateTime())->modify('-1 day');

(The latter takes into account this comment as it is a valid point.)

Should work fine for you here. See http://PHP.net/datetime

$date will be an instance of DateTime, a real DateTime object.

Answer 3

In same code use strtotime() its working.

$now = date("Y-m-d H:i:s");
$date = date("Y-m-d H:i:s", strtotime('-2 hours', strtotime($now)));

Answer 4

all you have to do is to alter your code to be

$now = strtotime(date("Y-m-d H:m:s"));
$date = date("Y-m-d H:m:s", strtotime('-24 hours', $now));