Php 合并两个数组并在没有'；不匹配

我正在构建一个日期请求，我需要构建一个数组，但要将其保持为每周五天的格式，这样我就可以轻松地将其输出到表中

我有当前工作日的数组，周一到周五，看起来像这样

$weekDays( [0] => 2016-12-19 [1] => 2016-12-20 [2] => 2016-12-21 [3] => 2016-12-22 [4] => 2016-12-23 ) 

以及一个用户的数组，其中包含他的个性化日期

$user( [0] => 2016-12-20 [1] => 2016-12-21 [2] => 2016-12-22)

正如你所看到的，这只是本周五次约会中的三次。我需要在日期匹配的地方合并这两个数组，但保持五天格式，如下所示

$userThisWeek([0] => NULL [1] => 2016-12-20 [2] => 2016-12-21 [3] => 2016-12-22 [4] => NULL)

我该怎么做呢？

类似这样的事情：

$userThisWeek = [];

foreach ($weekDays as $key => $day) {
    if (in_array($day, $user) {
        $userThisWeek[$key] = $day;
    } else {
        $userThisWeek[$key] = null;
    }
}

试试这个

// $weekDays( [0] => 2016-12-19 [1] => 2016-12-20 [2] => 2016-12-21 [3] => 2016-12-22 [4] => 2016-12-23 );
   // $user( [0] => 2016-12-20 [1] => 2016-12-21 [2] => 2016-12-22);
    $userThisWeek = array();
    foreach($weekDays as $key=>$value){
       if (array_search($value, $user) === FALSE)
          $userThisWeek[$key] = NULL;
       else
          $userThisWeek[$key] = $value;
    }