What can use for DateTime::diff() for PHP 5.2?

Question

Is there any function equivalent to DateTime::diff() in PHP 5.2?

My local server is PHP 5.3 and using DateTime::diff(). then I found that my live site uses PHP 5.2 and gives an error.

Fatal error: Call to undefined method DateTime::diff() in /var/www/some/other/dir/web/daikon/modules/projects/views/admin/log/admin_log_list.php on line 40

The PHP code:

 foreach ($logs as $key => $list){
 ...
 // show date in European way dd-mm-yyyy not in MySQL way yyyy-mm-dd
    $newdate =new DateTime($list['date']) ;
    echo "<td class=\"left\" width=\"8%\">".$newdate->format('d-m-Y')."</td>\n";
    $starttime = new DateTime($list['start_time']);
    echo "<td width=\"7%\">".date_format($starttime, 'H:i')."</td>\n";
    $finishtime = new DateTime($list['finish_time']);
    echo "<td width=\"8%\">".date_format($finishtime, 'H:i')."</td>\n";
    $timediff = 0;
    $interval = $starttime->diff($finishtime);
    $hours   = $interval->format('%h');
    $minutes = $interval->format('%i');
    $timediff = $hours * 60 + $minutes;

Answer 1

Spudley's answer doesn't work for me--subtracting any DateTime from another gives 0 on my system.

I was able to get it to work by using DateTime::format with the 'U' specifier (seconds since Unix epoch):

$start = new DateTime('2010-10-12');
$end = new DateTime();
$days = round(($end->format('U') - $start->format('U')) / (60*60*24));

This works on both my dev system (5.3.4) and my deployment system (5.2.11).