- var_dump: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$needYear=2018;
$needMonth=10;
$_startTime = strtotime('2018-10-31 00:00:00');
$_endTime = strtotime('2018-11-01 00:00:00');
var_dump(date('Y-n', $_startTime), date('Y-n', $_endTime), $needYear . '-' . $needMonth);
var_dump(date('Y-m-d', strtotime($needYear . '-' . $needMonth . ' last day')));