PHP时间比较和时间差如何计算

1.<?php
2. $zero1=date(“y-m-d h:i:s”);
3. $zero2=”2010-11-29 21:07:00′;
4. echo “zero1的时间为：”.$zero1.”<br>”;
5. echo “zero2的时间为：”.$zero2.”<br>”;
6. if(strtotime($zero1)<strtotime($zero2)){
7.  echo “zero1早于zero2′;
8. }else{
9.  echo “zero2早于zero1′;
10. }
11. ?>

上面是比较两个绝对时间的大小

<?php
$zero1=strtotime (date("y-m-d h:i:s")); //当前时间  ,注意H 是24小时 h是12小时
$zero2=strtotime ("2014-1-21 00:00:00");  //过年时间，不能写2014-1-21 24:00:00  这样不对
$guonian=ceil(($zero2-$zero1)/86400); //60s*60min*24h
echo "离过年还有<strong>$guonian</strong>天！";
?>

上面是倒计时小程序 实例代码

<?php
//PHP计算两个时间差的方法
$startdate="2010-12-11 11:40:00";
$enddate="2012-12-12 11:45:09";
$date=floor((strtotime($enddate)-strtotime($startdate))/86400);
$hour=floor((strtotime($enddate)-strtotime($startdate))%86400/3600);
$minute=floor((strtotime($enddate)-strtotime($startdate))%86400/60);
$second=floor((strtotime($enddate)-strtotime($startdate))%86400%60);
echo $date."天<br>";
echo $hour."小时<br>";
echo $minute."分钟<br>";
echo $second."秒<br>";

?>

<?php
/**
* 时间差计算
*
* @param Timestamp $time
* @return String Time Elapsed
* @author Shelley Shyan
* @copyright http://phparch.cn (Professional PHP Architecture)
*/
function time2Units ($time)
{
$year = floor($time / 60 / 60 / 24 / 365);
$time -= $year * 60 * 60 * 24 * 365;
$month = floor($time / 60 / 60 / 24 / 30);
$time -= $month * 60 * 60 * 24 * 30;
$week = floor($time / 60 / 60 / 24 / 7);
$time -= $week * 60 * 60 * 24 * 7;
$day = floor($time / 60 / 60 / 24);
$time -= $day * 60 * 60 * 24;
$hour = floor($time / 60 / 60);
$time -= $hour * 60 * 60;
$minute = floor($time / 60);
$time -= $minute * 60;
$second = $time;
$elapse = '';

$unitArr = array('年' =>'year', '个月'=>'month', '周'=>'week', '天'=>'day',
'小时'=>'hour', '分钟'=>'minute', '秒'=>'second'
);

foreach ( $unitArr as $cn => $u )
{
if ( $$u > 0 )
{
$elapse = $$u . $cn;
break;
}
}

return $elapse;
}

$past = 2052345678; // Some timestamp in the past
$now = time(); // Current timestamp
$diff = $now - $past;

echo '发表于' . time2Units($diff) . '前';
?>