Преобразование строки в массив?

$str = '{"update_id":540804803, "message":{"message_id":139,"from":{"id":23645226,"first_name":"Ivan","last_name":"Ivanov"},"chat":{"id":2459226,"first_name":"Ivan","last_name":"Ivanov","type":"private"},"date":1468266128,"text":"Cncjcj"}}';

var_dump(json_decode($str, true));

$json = '{"update_id":540804803, "message":{"message_id":139,"from":{"id":23645226,"first_name":"Ivan","last_name":"Ivanov"},"chat":{"id":2459226,"first_name":"Ivan","last_name":"Ivanov","type":"private"},"date":1468266128,"text":"Cncjcj"}}';
$array = json_decode($json,true);