strtotime() 函数将任何英文文本的日期或时间描述解析为 Unix 时间戳（自 January 1 1970 00:00:00 GMT 起的秒数）。
```
echo(strtotime("now") . "
");
echo(strtotime("15 October 1980") . "
");
echo(strtotime("+5 hours") . "
");
echo(strtotime("+1 week") . "
");
echo(strtotime("+1 week 3 days 7 hours 5 seconds") . "
");
echo(strtotime("next Monday") . "
");
echo(strtotime("last Sunday"));
```
php中如何给指定的日期加几天
```
$created_at = '2022-10-18';
$nextWeekDay = date("Y-m-d H:i:s",strtotime("$created_at +7 days"));
echo $nextWeekDay;
```
