Question

How can I get what date it will be after 31 days starting with $startDate, where $startDate is a string of this format: YYYYMMDD.

Thank you.

Answer 1

strtotime will give you a Unix timestamp:

$date = '20101007';
$newDate = strtotime($date.' + 31 days');

you can then use date to format that into the same format, if that’s what you need:

echo date('Ymd', $newDate);