- time: documentation ( source)
<?php
$myDate = DateTime::createFromFormat('mdY', '06102013');
echo $myDate->format('d.m.Y'), PHP_EOL;
echo $myDate->format('U'), PHP_EOL;
echo time();
$start = DateTime::createFromFormat('m/d/Y', '10/19/2015');
echo $start->setTime(0, 0), PHP_EOL;
echo $start->format('Y-m-d 00:00:00'), PHP_EOL;
echo $start->format('U');