在我的计算机和Linux服务器之间减去两个日期时的两个不同结果

I am using the same code on my computer and on my server at hostgator. Here's the code:

<?php
$checkout = "2014/03/11";
$checkin = "2014/03/09";

$checkin = date('Y/m/d', strtotime($checkin));
$checkout = date('Y/m/d', strtotime($checkout));

echo $checkin."<br />";
echo $checkout."<br />";

$nights = (strtotime($checkout) - strtotime($checkin)) / (60 * 60 * 24);

echo $nights;
?>

But I am getting different result. On my computer it display the correct answer which is "2". But on my server it displays "1.95833333333".

Can anyone tell me what's wrong?

Update:

Here's the output of the above code:

2014/03/09
2014/03/11
1.95833333333

You have to set the timezone with date_default_timezone_set($timezone) before using strtotime();