PHP处理日期和时间小整合

date_default_timezone_set('PRC'); //默认时区
$t = time();
$today=date("Y-m-d",time());
echo "今天：$today<br />"; 
echo "某一天：".date("Y-m-d",strtotime("18 june 2008"))."<br />"; 
echo "昨天：".date("Y-m-d",strtotime("-1 day"))."<br />"; 
echo "明天：".date("Y-m-d",strtotime("+1 day"))."<br />"; 
echo "一周后：".date("Y-m-d",strtotime("+1 week"))."<br />"; 
echo "一周零两天四小时两秒后：".date("Y-m-d G：H：s",strtotime("+1 week 2 days 4 hours 2 seconds"))."<br />"; 
echo "下个星期四：".date("Y-m-d",strtotime("next Thursday"))."<br />"; 
echo "上个周一：".date("Y-m-d",strtotime("last Monday"))."<br />"; 
echo "一个月前：".date("Y-m-d",strtotime("last month"))."<br />"; 
echo "一个月后：".date("Y-m-d",strtotime("+1 month"))."<br />"; 
echo "十年后：".date("Y-m-d",strtotime("+10 year"))."<br />";
echo "<br />=======================================================<br /><br />";
$w = date("w",time()); //获取今天是本周周几
echo "今天是星期$w<br />"; 
$d=array("日","一","二","三","四","五","六");
$whatday="星期".$d[date("w",strtotime($today))]; //获取今天星期几
echo "今天是$whatday<br />"; 
$d0 = date("Y-m-d",strtotime("-$w day",$t)); //周开始 
echo "本周周日是：$d0<br />"; 
$d6 = date("Y-m-d",strtotime((6-$w)." day",$t)); //周结束 
echo "本周周六是：$d6<br />"; 

echo "本周周日是：".date("Y-m-d",strtotime("Sunday"))."<br />";  //周开始 
echo "本周周六是：".date("Y-m-d",strtotime("Saturday"))."<br />";  //周结束
echo "上周周日是：".date("Y-m-d",strtotime("last Sunday"))."<br />";  //上周开始 
echo "上周周六是：".date("Y-m-d",strtotime("last Saturday"))."<br />";  //上周结束
echo "<br />=======================================================<br /><br />";
$time = abs((strtotime("2012-12-21") - strtotime(date("Y-m-d")))/86400);//获取两个日期之间的天数差
echo "距离世界末日还有：$time 天<br />";  //上周结束