Add an associated pair to a PHP array

Question

I have an array, i tried writing

array_push($json['Request']['Header'], "key" => "val");

but i received an error. Writing the below works but it adds an array instead of just the key/val

array_push($json['Request']['Header'], array("key" => "val"));

..
[0] => Array
        (
            [key] => val
        )

//i would like
...
[key] => val

Answer 1

Try

$json['Request']['Header']['key'] = 'val';

Answer 2

Why not simply write:

$json['Request']['Header'] = array();
$json['Request']['Header']['key'] = 'val';

Answer 3

Use the addition operator to append an associative array:

$json['Request']['Header'] += array("key" => "val");