如何处理PHP中的XML和JSON数据

<?xml version="1.0" encoding="UTF-8"?>
<catalog>
  <book id="001">
    <author>John Doe</author>
    <title>The PHP Cookbook</title>
  </book>
  <book id="002">
    <author>Jane Smith</author>
    <title>Web Design for Beginners</title>
  </book>
  <book id="003">
    <author>Jim Johnson</author>
    <title>Database Administration</title>
  </book>
</catalog>

$xml = simplexml_load_file('books.xml');

foreach ($xml->book as $book) {
  echo (string)$book->author . ' - ' . (string)$book->title . '<br>';
}

{
  "catalog": [
    {
      "id": "001",
      "author": "John Doe",
      "title": "The PHP Cookbook"
    },
    {
      "id": "002",
      "author": "Jane Smith",
      "title": "Web Design for Beginners"
    },
    {
      "id": "003",
      "author": "Jim Johnson",
      "title": "Database Administration"
    }
  ]
}

$json = '{"catalog":[{"id":"001","author":"John Doe","title":"The PHP Cookbook"},{"id":"002","author":"Jane Smith","title":"Web Design for Beginners"},{"id":"003","author":"Jim Johnson","title":"Database Administration"}]}';

$data = json_decode($json);

foreach ($data->catalog as $item) {
  echo $item->author . ' - ' . $item->title . '<br>';
}