PHP上个月获取特定日期的时间戳[关闭]

Question

Can I use strtotime() to obtain the timestamp for a given day 'last month' and if not what is the most efficient way of doing this?

This is the kind of thing I want

strtotime("5 last Month");

instead of

$time_day= 5;
$time_month= date("m");
$time_year= date("Y");

if($time_month<1){
$time_month=12;
$time_year--;
}else{
$time_month--;
}

$date=mktime(0,0,0,$time_month,$time_day,$time_year);

Answer 1

Unfortuantely what you want to do is not currently possible using strtotime() in PHP. Here's how to achieve what you want in one line, using mktime() and date():

$timestamp = mktime(0, 0, 0, date('n') - 1, 21);

The above code will find the timestamp for the 21st day of the previous month. Just swap 21 for whatever you want.

This works because:

Values less than 1 (including negative values) reference the months in the previous year in reverse order, so 0 is December, -1 is November, etc. [PHP Documentation]

So if the month was 1 (January), you would be running mktime() with 0 as the month value, which means 'December in the previous year'.