尝试从多维数组中获取Key的值

Question

I have an array thus (got this using var_dump):

array
  0 => 
    array
      'post_id' => string '6' (length=1)
  1 => 
    array
      'post_id' => string '9' (length=1)

I want to get the key when I have just the post_id. For example, I want '0' returned if I have '6' and '1' if I have '9'. I have tried:

$key = array_keys($subs, array_keys($subs[??], 6));

given that the $subs is the array. The issue is, I don't know how to iterate through the array 'within' the 'parent' array, hence, the '??'

Answer 1

I would use array_filter() and use to do this. Like this:

$array; // your array
$needle; // the value you are looking for
$filtered_array = array_filter($array, function ($element) use ($needle) {
    return ($element['post_id'] === $needle);
});

$matching_keys = array_keys($filtered_array);

The array_filter() will filter down the input array to only those array element arrays that have a value for post_id that matches the value of $needle. You can use array_keys to get the key values for the remaining element(s) after the filter has been applied.