$start = #שעת התחלה#;
$end = #שעת סיום#;

list($startHours, $startMinutes) = explode(‘:’, $start);
list($endHours, $endMinutes) = explode(‘:’, $end);

$startTotalMinutes = ($startHours * 60) + $startMinutes;
$endTotalMinutes = ($endHours * 60) + $endMinutes;

if ($endTotalMinutes < $startTotalMinutes) {
$endTotalMinutes += 1440;
}

$diffMinutes = $endTotalMinutes – $startTotalMinutes;

$diffHours = floor($diffMinutes / 60);
$diffMinutes = $diffMinutes % 60;

if ($diffMinutes < 10) {
$diffMinutes = "0" . strval($diffminutes);
}

return strval($diffHours) . ':' . strval($diffminutes);