Php 通过内部数组键和值获取外部数组键

这里我需要输出3，key-其中

question\u id\u count

的值为3

您可以迭代数组，并在当前对象属性匹配时保存key：

5 Array 

( 
  [0] => stdClass Object ( [question_id] => 1 [question_id_count] => 3 ) 
  [1] => stdClass Object ( [question_id] => 2 [question_id_count] => 3 ) 
  [2] => stdClass Object ( [question_id] => 3 [question_id_count] => 3 ) 
  [3] => stdClass Object ( [question_id] => 4 [question_id_count] => 5 ) 
  [4] => stdClass Object ( [question_id] => 5 [question_id_count] => 3 ) 
)

$outerKey = null;
foreach($array as $key => $value){
    if($value->question_id == 3){
        $outerKey = $key;
        break;
    }
}
var_dump($outerKey); //int(2)