<?php
$date_from1 = new DateTime('1-9-2016');
$date_from=$date_from1->format('Y-m-d');
$date_to1 = new DateTime('30-9-2016');
$date_to=$date_to1->format('Y-m-d');
$diff1=$date_from1->diff($date_to1);
$diff2= $diff1->format('%R %a days');
$interval = new DateInterval('P1D');
preg_match_all('!\d+!', $diff2, $matches); //use that to get only number from diff2
for($i=0; $i <= $matches[0][0]; $i++) //$matches return diff2 only number of days
{
$this_date= $i? $date_from1->add($interval): $date_from1;
echo $this_date->format('Y-m-d') . "\r\n";
}