多维数组 PHP-JSON

如何在 PHP 中创建一个数组，使用 json_encode() 变成具有以下结构的东西：

Array(
[1] => Array(
    [id] => 1
    [data] => 45
)
[2] => Array(
    [id] => 3
    [data] => 54
)
);

尝试这样的事情：

//initialize array
$myArray = array();

//set up the nested associative arrays using literal array notation
$firstArray = array("id" => 1, "data" => 45);
$secondArray = array("id" => 3, "data" => 54);

//push items onto main array with bracket notation (this will result in numbered indexes)
$myArray[] = $firstArray;
$myArray[] = $secondArray;

//convert to json
$json = json_encode($myArray);