Php 减去两个日期以显示天数

上面的php代码显示两个日期的差异，但我想从datetime1减去这两个日期datetime2，datetime1甚至应该显示负值。

试试这个

<?php
    $datetime1 = new DateTime("$da[tofollowon]");

    $datetime2 = new DateTime();

    $difference = $datetime1->diff($datetime2);

    $days = $difference->days;
?>

试一试

更多详情：

 $d1 = strtotime("2014-01-10"); // or your date as well
 $d2 = strtotime("2014-01-01");
 $datediff = $d1 - $d2;
 echo floor($datediff/(60*60*24)).' days';

$start = strtotime('2010-01-25');
$end = strtotime('2010-02-20');
$days_between = ceil(abs($end - $start) / 86400);