I'm a little unsure why this is not able to find the last day of the previous month. Every steps seems to be working correctly, except when the final date is created.

<?php

$currentMonth = date('n');
$currentYear = date('Y');

if($currentMonth == 1) {
    $lastMonth = 12;
    $lastYear = $currentYear - 1;
}
else {
    $lastMonth = $currentMonth -1;
    $lastYear = $currentYear;
}

if($lastMonth < 10) {
    $lastMonth = '0' . $lastMonth;
}

$lastDayOfMonth = date('t', $lastMonth);

$lastDateOfPreviousMonth = $lastYear . '-' . $lastMonth . '-' . $lastDayOfMonth;

$newLastDateOfMonth = date('F j, Y', strtotime($lastDateOfPreviousMonth));

?>

$lastDateOfPreviousMonth is returning 2012-09-30 as expected; however, after trying to convert it to September 30, 2012 - $newLastDateOfMonth is returning October 1, 2012. Where do I seem to be going wrong?

EDIT: If using date("t/m/Y", strtotime("last month")); or date('Y-m-d', strtotime('last day of previous month')); will either of these still be viable given 2013-01-01, i.e. will they account for the change in year?

php datetime
Edit
Report