Adding 30 minutes to time formatted as H:i in PHP - php

Question

Having a nightmare at the moment and just can't see why it isn't working
I have a value in the form H:i (ie 10:00, 13:30) etc called $time
What I want to do is create two new values, $startTime which is 30 mins before $time and $endTime which is 30 mins after $time
I have tried the following but just doesn't seem to want to work
$startTime = date("H:i",strtotime('-30 minutes',$time));
$endTime = date("H:i",strtotime('+30 minutes',$time));
If I pass through 10:00 as $time and echo out both $startTime and $endTime I get:
$startTime = 00:30
$startTime = 01:30

Answer 1

$time = strtotime('10:00');
$startTime = date("H:i", strtotime('-30 minutes', $time));
$endTime = date("H:i", strtotime('+30 minutes', $time));

Answer 2

In order for that to work $time has to be a timestamp. You cannot pass in "10:00" or something like $time = date('H:i', '10:00'); which is what you seem to do, because then I get 0:30 and 1:30 as results too.
Try
$time = strtotime('10:00');
As an alternative, consider using DateTime (the below requires PHP 5.3 though):
$dt = DateTime::createFromFormat('H:i', '10:00'); // create today 10 o'clock
$dt->sub(new DateInterval('PT30M')); // substract 30 minutes
echo $dt->format('H:i'); // echo modified time
$dt->add(new DateInterval('PT1H')); // add 1 hour
echo $dt->format('H:i'); // echo modified time
or procedural if you don't like OOP
$dateTime = date_create_from_format('H:i', '10:00');
date_sub($dateTime, date_interval_create_from_date_string('30 minutes'));
echo date_format($dateTime, 'H:i');
date_add($dateTime, date_interval_create_from_date_string('1 hour'));
echo date_format($dateTime, 'H:i');

Answer 3

I usually take a slightly different track to achieve this:
$startTime = date("H:i",time() - 1800);
$endTime = date("H:i",time() + 1800);
Where 1800 seconds = 30 minutes.

Answer 4

Your current solution does not work because $time is a string - it needs to be a Unix timestamp. You can do this instead:
$unix_time = strtotime('January 1 2010 '.$time); // create a unix timestamp
$startTime date( "H:i", strtotime('-30 minutes', $unix_time) );
$endTime date( "H:i", strtotime('+30 minutes', $unix_time) );

Answer 5

$time = 30 * 60; //30 minutes
$start_time = date('Y-m-d h:i:s', time() - $time);
$end_time = date('Y-m-d h:i:s', time() + $time);

Answer 6

echo date( "Y-m-d H:i:s", strtotime("2016-10-10 15:00:00")+(60*30) );//2016-10-10 15:30:00
or
echo date( "H:i:s", strtotime("15:00:00")+(60*30) ); // 15:30:00
or
echo date( "H:i:s", strtotime(date("H:i:s"))+(60*30) ); // 15:30:00

Answer 7

Just to expand on previous answers, a function to do this could work like this (changing the time and interval formats however you like them according to this for function.date, and this for DateInterval):
// Return adjusted start and end times as an array.
function expandTimeByMinutes( $time, $beforeMinutes, $afterMinutes ) {
$time = DateTime::createFromFormat( 'H:i', $time );
$time->sub( new DateInterval( 'PT' . ( (integer) $beforeMinutes ) . 'M' ) );
$startTime = $time->format( 'H:i' );
$time->add( new DateInterval( 'PT' . ( (integer) $beforeMinutes + (integer) $afterMinutes ) . 'M' ) );
$endTime = $time->format( 'H:i' );
return [
'startTime' => $startTime,
'endTime' => $endTime,
];
}
$adjustedStartEndTime = expandTimeByMinutes( '10:00', 30, 30 );
echo '<h1>Adjusted Start Time: ' . $adjustedStartEndTime['startTime'] . '</h1>' . PHP_EOL . PHP_EOL;
echo '<h1>Adjusted End Time: ' . $adjustedStartEndTime['endTime'] . '</h1>' . PHP_EOL . PHP_EOL;