<?php
    $end_date = date('2021-11-28'); //디데이 날짜
    $d_day = floor((strtotime($end_date) - strtotime(date('Y-m-d'))) / 86400);
    if ($d_day < 0) {
      $d_day = '이벤트 종료';
    } else {
      $d_day = $d_day;
    }
?>

<?php echo $d_day?>