itmalex

function diff($startTime, $endTime) 
{
    $startDate = new \DateTime($startTime);
    $endDate = new \DateTime($endTime);
    
    if ($startTime == $endTime) {
        return 24;
    }

    if ($startDate >= $endDate) {
        $startDate = $startDate->modify('-1 day');
    }

    $diff = $startDate->diff($endDate);
    return $diff->h;
}

print(diff('05:00:00', '04:00:00'));