บทความ เทคนิคการเขียน php

$date="2008-02-14";
list($yy,$mm,$dd)=explode("-",$date);
//  mktime(hour,minute,second,month,day,year)
$nowdate = date('Y-m-d',mktime(0,0,0,$mm,$dd,$yy));
echo $nowdate."<br />";
$newdate = date('Y-m-d',mktime(0,0,0,$mm,$dd+13,$yy));
echo $newdate;

$a = '2008-03-08';
$b = '2008-02-28';
$div = (strtotime($a) - strtotime($b)) / (60 * 60 * 24);
echo $div;