Kindah rounds off dates

date_floor.php

<?php

$defaults = array(
	'month' => 'january',
	'day' => 1,
	'hour' => 0,
	'minute' => 0,
	'second' => 0
);

$givenunit = 'month';
$date = '4 Apr 12 23:38:03';

$conv = date('Y-m-d H:i:s', strtotime($date));
//$conv = '2012-04-04 23:38:03';
list($d, $t) = explode(' ', $conv);
$arr = array_merge(explode('-', $d), explode(':', $t));

$newdate = array(array_shift($arr));
$unitreached = false;
foreach ($defaults as $unit => $default) {
	if ($unitreached) {
	 	$newdate[] = $default;
	 	continue;
	}

	if (!$unitreached && $unit == $givenunit) {
		$unitreached = true;
	}

	$newdate[] = array_shift($arr);
}

echo implode(' ', $newdate);