- mktime: documentation ( source)
- date: documentation ( source)
<?php
echo mktime(0, 0, 0, date("m") , date("d")+1, date("Y")).'<br>';
echo mktime(0, 0, 0, date("m")-1, date("d"), date("Y")).'<br>';
echo mktime(0, 0, 0, date("m"), date("d"), date("Y")+1).'<br>';