[php] PHP Adding 15 minutes to Time value

I have a form that receives a time value:

$selectedTime = $_REQUEST['time'];

The time is in this format - 9:15:00 - which is 9:15am. I then need to add 15 minutes to this and store that in a separate variable but I'm stumped.

I'm trying to use strtotime without success, e.g.:

$endTime = strtotime("+15 minutes",strtotime($selectedTime)));

but that won't parse.

strtotime returns the current timestamp and date is to format timestamp

  $date=strtotime(date("h:i:sa"))+900;//15*60=900 seconds
  $date=date("h:i:sa",$date);

This will add 15 mins to the current time

Quite easy

$timestring = '09:15:00';
echo date('h:i:s', strtotime($timestring) + (15 * 60));

You can use below code also.It quite simple.

$selectedTime = "9:15:00";
echo date('h:i:s',strtotime($selectedTime . ' +15 minutes'));

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):

(I've also written an alternate form of the below function here.)

// Return adjusted time.

function addMinutesToTime( $time, $plusMinutes ) {

    $time = DateTime::createFromFormat( 'g:i:s', $time );
    $time->add( new DateInterval( 'PT' . ( (integer) $plusMinutes ) . 'M' ) );
    $newTime = $time->format( 'g:i:s' );

    return $newTime;
}

$adjustedTime = addMinutesToTime( '9:15:00', 15 );

echo '<h1>Adjusted Time: ' . $adjustedTime . '</h1>' . PHP_EOL . PHP_EOL;

Though you can do this through PHP's time functions, let me introduce you to PHP's DateTime class, which along with it's related classes, really should be in any PHP developer's toolkit.

// note this will set to today's current date since you are not specifying it in your passed parameter. This probably doesn't matter if you are just going to add time to it.
$datetime = DateTime::createFromFormat('g:i:s', $selectedTime);
$datetime->modify('+15 minutes');
echo $datetime->format('g:i:s');

Note that if what you are looking to do is basically provide a 12 or 24 hours clock functionality to which you can add/subtract time and don't actually care about the date, so you want to eliminate possible problems around daylights saving times changes an such I would recommend one of the following formats:

!g:i:s 12-hour format without leading zeroes on hour

!G:i:s 12-hour format with leading zeroes

Note the ! item in format. This would set date component to first day in Linux epoch (1-1-1970)

Current date and time

$current_date_time = date('Y-m-d H:i:s');

15 min ago Date and time

$newTime = date("Y-m-d H:i:s",strtotime("+15 minutes", strtotime($current_date)));