Question

I have a PHP script for a select dropdown box to display times in 15 minute intervals; however, I’d like to have it default to the closest current time (rounding up or down based on 15 minute interval). Any ideas?

date_default_timezone_set($_SESSION['TIME_ZONE'])

<label id="time_label" for="time" class="label">Time:</label>

<select id="time" name="time">

    <option value="">Select</option>

    <?

       $start = strtotime('12:00am');
       $end = strtotime('11:59pm');
       for ($i = $start; $i <= $end; $i += 900){
           echo '<option>' . date('g:i a', $i);
       }
    ?>

</select>

Answer 1

Here is a convenient way to get the current time rounded up or down:

$time = time();
$rounded_time = $time % 900 > 450 ? $time += (900 - $time % 900):  $time -= $time % 900;

$start = strtotime('12:00am');
$end = strtotime('11:59pm');
for( $i = $start; $i <= $end; $i += 900) 
{
    $selected = ( $rounded_time == $i) ? ' selected="selected"' : '';
    echo '<option' . $selected . '>' . date('g:i a', $i) . '</option>';
}

You can use the following demo to test, just add either 450 or 900 to the $time variable.

Edit: As per the comments below, there is one condition that will fail because the rounded up time results in a rollover to the next day. To fix it, modify the $selected line to:

$selected = ( ($rounded_time - $i) % (86400) == 0) ? ' selected="selected"' : '';

This ignores the date portion and just checks the time. I’ve updated the demo below to reflect this change.

Demo