<?php
function GetLastDayOfThisMonth () {
list ($month, $year) = explode ('-', date ('m-Y'));
$year = ((int)$month === 12)?$year+1:$year;
$month = ((int)$month + 1 === 13)?1:$month+1;
$lastDay = mktime (0, 0, 0, $month, 0, $year);
return strftime ('%d', $lastDay);
}
?>