如何获得相对于一年中的一周的前一年的日期

Question

How can I get the same day of the same ISO-8601 week number but in the previous year using php?

I am familiar with extracting this soft of information from a time stamp. Is there a built-in way for me to go from day of week, week of year and year to time stamp?

Answer 1

You can use the combination of both date and strtotime like so:

// get the timestamp
$ts = strtotime('today');

// get year, week number and day of week
list($year, $week, $dow) = explode('-', date('Y-W-N', $ts));

// use the "YYYY-WXX-ZZ" format    
$format = ($year - 1) . "-W$week-$dow";
echo date('Y-m-d', strtotime($format)), PHP_EOL;

Answer 2

You can do this with strtotime :

$now = time(); // Mon, 12 Nov 2012
$targetYear = date('Y', $now) - 1; // 2011
$targetWeek = date('\\WW-N', $now); // W46-1
$lastYear = strtotime($targetYear . $targetWeek); // Mon, 14 Nov 2011

Answer 3

Try this one:

$date = "2012-11-13";
echo getLastYearWeek($date);
function getLastYearWeek($date)
{
    $last_year = date("Y-m-d W N", strtotime("-52 Weeks ".$date));

    return $last_year;
}

Or just,

$last_year = date("Y-m-d W N", strtotime("-52 Weeks ".$date));

Use this for reference.

Answer 4

I think you are looking for mktime. have a look here http://php.net/manual/en/function.mktime.php