如何从周数中获取开始日期

您可以使用此

  echo $weeknumber = date('W', strtotime('18-10-2012'));
  $gendate = new DateTime();
  $gendate->setISODate(2015,$weeknumber,4); //year , week num , day
  echo $gendate->format('d-m-Y'); //"prints" 

使用此

你需要像这样改变strtotime('10-02-2015'))

$date_string = "2012-10-18";
$weeknumber =  date("W", strtotime($date_string));
//get the date from week number

等日期

$gendate = new DateTime();
$gendate->setISODate(2013,$weeknumber ,4); //year , week num , day
echo $gendate->format('d-m-Y'); //"prints"  26-12-2013

不要将strtotime()和date()函数与DateTime类混合使用。它可以在没有它们的情况下简单地完成，只需DateTime，如：

$date = new DateTime('10-02-2015');
$date->setISODate($date->format('o'), $date->format('W'));
echo $date->format('d-m-Y');

演示