- key: documentation ( source)
<?php
$books["978-0743261690"] = "Gilgamesh";
$books["978-0060931957"] = "The Odyssey";
$books["978-0192840509"] = "Aesop's Fables";
$books["978-0520227040"] = "Mahabharta";
$books["978-0393320978"] = "Beowulf";
?><html>
<head>
<title>Five Great Books</title>
</head>
<body>
<h1>Five Great Books</h1>
<ul>
<?php foreach($books as $book) { ?>
<li><?php echo key($book); ?></li>
<?php } ?>
</ul>
</body>
</html>