倒计时

<?php
$time1=strtotime(date("Y-m-d H:i:s"));
$tim2=strtotime("2015-10-01 00:00:00");
$time3=strtotime("2016-01-01");
$sub1=ceil(($tim2-$time1)/3600);//小时
$sub2=ceil(($tim2-$time1)/86400);//天
$sub3=ceil(($time3-$time1)/86400);
echo "距离2015年国庆还有<font color='red'>$sub1</font>小时<br>";
echo "距离2015年国庆还有<font color='red'>$sub2</font>天<br>";
echo "距离2016年元旦还有<font color='red'>$sub3</font>天";