How to subtract 1 day 16 hours from datetime in PHP

Question

I'm trying subtracting Day and Hour from given date time example:

$schedule_date_time = '2016-02-29 08:30 PM';
echo date( "Y-m-d h:i a", strtotime("-1 day 16 hours", strtotime($schedule_date_time)) );

It gives me following result: 2016-02-29 12:30 pm

Which is not correct...

But If I do this :

$schedule_date_time = '2016-02-29 08:30 PM';
    echo date( "Y-m-d h:i a", strtotime("-1 day -16 hours", strtotime($schedule_date_time)) );

It gives me following result: 2016-02-28 04:30 am

which is correct but is not possible for me to identify and put minus sign in string just before the integer.

Answer 1

Use date_sub/DateTime::sub.

$date = date_create("2016-02-29 08:30 PM") ;
date_sub($date, date_interval_create_from_date_string('1 day 16 hours'));
echo date_format($date, 'Y-m-d h:i a'); // 2016-02-28 04:30 am

If you want add an amount of time instead of subtracts it, use date_add instead.