defined month last date in php code example

Example 1: php last day of month

$a_date = "2009-11-23";
echo date("Y-m-t", strtotime($a_date));

Example 2: get last month using php

//Last month
$lastMonth = Date("F", strtotime("first day of previous month");
$nextMonth = Date("F", strtotime("first day of next month");