- var_dump: documentation ( source)
- date_default_timezone_set: documentation ( source)
<?php
$_POST['expectedReturn'] = 'PT4H';
$tmpER = $_POST['expectedReturn'];
date_default_timezone_set('America/New_York');
$nowDate = new \DateTime();
$hrDate = clone $nowDate;//test
$tmpInterval = new \DateInterval($tmpER);
$hrDate->add($tmpInterval);
$tmpDate = $hrDate->format('l, M. d, Y - h:ia');
var_dump($tmpDate);