How can the second parameter of json_decode be used to return only arrays?

When using the `json_decode` function in PHP, the second parameter can be used to specify whether the returned data should be converted into associative arrays or objects. To return only arrays, you can set the second parameter to `true`. This will ensure that the JSON data is decoded into arrays instead of objects.

$json_data = '{"name": "John Doe", "age": 30}';
$array_data = json_decode($json_data, true);

// $array_data will now contain the decoded JSON data as an associative array