- date_create: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
- date_format: documentation ( source)
<?php
$week = "+1 weeks"; //"+". $dt . "week"
$str = 'jan 01, 2016';//$jinput->get('start_date')
$date = date_create($str);
$choosendate = date_format($date, "m/d/Y");
$newdate = strtotime($week, strtotime($choosendate));
echo date('M d, Y', $newdate);