strtotime（） code>使用30天，二月（今年）只有28天，所以不会在二月份生效。您可以使用当前日期 d 或 j ，并减去将始终将您放在上个月（ -29天）：

strtotime() uses 30 day months and there are only 28 in days in February (this year) so will not yield a valid date in February. You could use the current day d or j and subtract that which will always put you in the previous month (-29 days):

$prevmonth = date('M', strtotime('-' . date('d') . ' days'));

这将获得 12月从 January 。