How to count days between two dates in PHP?

If I have a couple of strings $startDate and $endDate which are set to (for instance) "2011/07/01" and "2011/07/17" (meaning 1 July 2011 and 17 July 2011). How would I count the days from start date to end date? In the example given, it would be 17 days.

Here is the raw way to do it

$startTimeStamp = strtotime("2011/07/01");
$endTimeStamp = strtotime("2011/07/17");

$timeDiff = abs($endTimeStamp - $startTimeStamp);

$numberDays = $timeDiff/86400;  // 86400 seconds in one day

// and you might want to convert to integer
$numberDays = intval($numberDays);

Use DateTime::diff (aka date_diff):

$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);

Or:

$datetime1 = date_create('2009-10-11');
$datetime2 = date_create('2009-10-13');
$interval = date_diff($datetime1, $datetime2);

You can then get the interval as a integer by calling $interval->days.

PHP has a date_diff() function to do this.

<?php
$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days');
?>

Source: http://www.php.net/manual/en/datetime.diff.php