- var_dump: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
- sprintf: documentation ( source)
<?php
$date = sprintf('%04d-%02d', 2016, 02);
$begin_date = $date . '-01';
$end_date = $date . '-' . date('t', strtotime($date . '-05'));
var_dump($begin_date);
var_dump($end_date);