- time: documentation ( source)
- mktime: documentation ( source)
<?php
$target_days = mktime(0,0,0,12,31,2013);// modify the birth day 12/31/2013
$today = time();$diff_days = ($target_days - $today);$days = (int)($diff_days/86400);print "Days till next birthday: $days days!";?>