strtotime.php

<?php $tmp =array (
  'Version' => 
  array (
    0 => '2.3.5',
    1 => '2.3.1',
    2 => '2.3',
    3 => '2.2',
    4 => '2.1.2',
    5 => '2.1.1',
    6 => '2.1',
    7 => '2.0',
    8 => '1.3',
    9 => '1.2',
    10 => '1.1.0',
    11 => '1.0.1',
    12 => '1.0',
  ),
  'Date' => 
  array (
    0 => 'Oct 10, 2014',
    1 => 'Sep 18, 2014',
    2 => 'Jul 07, 2014',
    3 => 'Apr 09, 2014',
    4 => 'Feb 25, 2014',
    5 => 'Feb 22, 2014',
    6 => 'Feb 12, 2014',
    7 => 'Dec 18, 2013',
    8 => 'Sep 18, 2013',
    9 => 'Jul 12, 2013',
    10 => 'May 23, 2013',
    11 => 'May 07, 2013',
    12 => 'Apr 28, 2013',
  ),
);


if(!empty($tmp)){
	for ($i=0; $i < count($tmp['Date']); $i++) { 
		$tmp['Date'][$i] = strtotime($tmp['Date'][$i]);
		pre_print_r(date('Y-m-d', $tmp['Date'][$i]));
	}
}