两个固定格式的时间转换为时间戳，并进行比较

<?php
//转换为时间戳
$time1="2003-02-23 12:06:52";
$time2="2009-01-08 23:11:52";

function stamptime($time1,$time2){
   $stamptime1=strtotime("$time1");
   $stamptime2=strtotime("$time2");
   //计算相差时间
   $stamptime=$stamptime2-$stamptime1;
       //转换成天数（计算出大于$stamptime的最小天数）
     $days=ceil($stamptime/86400);
     return $days;
}
echo $time1."<br>与<br>".$time2."<br>间相差：".stamptime($time1,$time2)."天";

?>