Online PHP editor | output for X0pJg

<?php function oneWeek(\DateTimeInterface $date): \DateTimeInterface { $week = new \DateInterval('P1W'); $inOneWeek = $date->add($week); return $inOneWeek; } $d1 = new \DateTime(); $d2 = new \DateTimeImmutable(); $o1 = oneWeek($d1); $o2 = oneWeek($d2); $f = 'F jS, Y'; echo 'One week from ' . $d1->format($f) . ' is ' . $o1->format($f) . "\n"; echo 'One week from ' . $d2->format($f) . ' is ' . $o2->format($f) . "\n";