PHP date_diff() 函数-计算日期差值

<?php
$today = date('Y-m-d H:i:s');
$datetime_start = date_create(date('Y-m-d',strtotime($today)));
$datetime_end = date_create(date('Y-m-d',strtotime('2021-12-01')));
$days = date_diff($datetime_start, $datetime_end)->days;
//echo $diff->format("%R%a days");
echo $days; 

######输出------22