計算PHP 往前日後推幾天日期

<?php 
date_default_timezone_set('PRC'); //默認時區 
echo "今天:",date("Y-m-d",time()),"<br>"; 
echo "今天:",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 "一週後:",date("Y-m-d",strtotime("+1 week")), "<br>"; 
echo "一週零兩天四小時兩秒後:",date("Y-m-d G:H:s",strtotime("+1 week 2 days 4 hours 2 seconds")), "<br>"; 
echo "下個星期四:",date("Y-m-d",strtotime("next Thursday")), "<br>"; 
echo "上個週一:".date("Y-m-d",strtotime("last Monday"))."<br>"; 
echo "一個月前:".date("Y-m-d",strtotime("last month"))."<br>"; 
echo "一個月後:".date("Y-m-d",strtotime("+1 month"))."<br>"; 
echo "十年後:".date("Y-m-d",strtotime("+10 year"))."<br>"; 

?>

php判斷一個日期距今天還有多少天 

複製代碼代碼以下:

<?php 
echo (strtotime('2020-5-20′)-strtotime(date(「Y-m-d」)))/86400; 

?>