Start and end days of week based on the first day of the week

Source code viewer
// 0 - Sunday, 1 - Monday
$week_start_day = 0;
 
$date_time_from = new DateTime('now');
$date_time_to = clone $date_time_from;
 
$this_week_first_day =
  $date_time_from->setISODate(
    $date_time_from->format('Y'),
    $date_time_from->format('W'),
    $week_start_day
  );
$this_week_last_day =
  $date_time_to->setISODate(
    $date_time_to->format('Y'),
    $date_time_to->format('W'),
    (6 + $week_start_day)
  );
 
// Set time to the start of day and end of day, correspondingly.
$this_week_first_day->modify('00:00:00.000000');
$this_week_last_day->modify('23:59:59.999999');
Programming Language: PHP