Question

Let’s say your creating an application that needs to send you an email monthly. The date start date is FEB 29, 2012. How do you deal with that for next year since there is no FEB 29, 2013. Likewise if the start date is JAN 31, there is no FEB 31 or APR 31, and so on…

Answer 1

Simply use the DateTime class which is perfect for this:

If I want the date 1 month from 29/2/2012:

$date = new DateTime('2012-02-29'); // "start date"
$date->add(new DateInterval('P1M')); //one month later
echo $date->format('Y-m-d') . "\n"; //2012-03-29

And a year later:

$date = new DateTime('2012-02-29'); //start
$date->add(new DateInterval('P1Y')); //one year later
echo $date->format('Y-m-d') . "\n"; //2013-03-01 

Using this, you can easily caculate any date intervals you require.