如何使用PHP从数组中获取key的值？

Question

我的数组如下：

Array
(
    [0] => Array
        (
            [week_startDate] => 2019-02-01
            [week_endDate] => 2019-02-03
        )

    [1] => Array
        (
            [week_startDate] => 2019-02-04
            [week_endDate] => 2019-02-10
        )

    [2] => Array
        (
            [week_startDate] => 2019-02-11
            [week_endDate] => 2019-02-17
        )

    [3] => Array
        (
            [week_startDate] => 2019-02-18
            [week_endDate] => 2019-02-24
        )

    [4] => Array
        (
            [week_startDate] => 2019-02-25
            [week_endDate] => 2019-02-28
        )

)

我希望在匹配 week_startDate 时获得 week enddate 的键值。假设 week_startDate 是：

Case1期望值：week startdate 匹配数组中的2019-02-01，然后返回2019-02-03

Case2期望值：week startdate 匹配数组中的2019-02-18，然后返回2019-02-244

可以使用数组函数或其他方式吗？

Answer 1

$expectedDate = '2019-02-11';
foreach($arr as $key => $val){
  if($expectedDate ==$val['week_startDate']){
   return $val['week_endDate'];
  }
}

Another solution

$startDate = '2019-02-01';
$k = array_search($startDate, array_column($array, 'week_startDate'));
if ($k !== false) {
   echo $array[$k]['week_endDate'];
}