Pretty-Printing JSON with PHP

I'm building a PHP script that feeds JSON data to another script. My script builds data into a large associative array, and then outputs the data using json_encode. Here is an example script:

$data = array('a' => 'apple', 'b' => 'banana', 'c' => 'catnip');
header('Content-type: text/javascript');
echo json_encode($data);

The above code yields the following output:

{"a":"apple","b":"banana","c":"catnip"}

This is great if you have a small amount of data, but I'd prefer something along these lines:

{
    "a": "apple",

    "b": "banana",
    "c": "catnip"
}

Is there a way to do this in PHP without an ugly hack? It seems like someone at Facebook figured it out.

Answer

PHP 5.4 offers the JSON_PRETTY_PRINT option for use with the json_encode() call.

http://php.net/manual/en/function.json-encode.php

...
$json_string = json_encode($data, JSON_PRETTY_PRINT);