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PHP Build a Basic PHP Website (2018) Listing and Sorting Inventory Items Array Keys

Posted by Kerri-Ann Bates
Kerri-Ann Bates
15,422 Points

How do I echo just the key from an associative array?

For example: 

$x = array('dog' => 'Spot', 'cat' => 'Bella');

Using the foreach loop, how can I echo 'dog'.

<?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 $isbn => $book) { ?>
            <li><?php echo $books . " (" . $isbn . ")"; ?></li>
        <?php } ?>
    </ul>
</body>
</html>

I get an error saying: Notice: Array to string conversion in index.php on line 17 Array (978-0743261690). Thank you.

index.php 
<?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 $isbn => $book) { ?>
            <li><?php echo $book; ?></li>
        <?php } ?>
    </ul>
</body>
</html>

1 Answer

Rich Donnellan
MOD
Rich Donnellan
Treehouse Moderator 27,671 Points
Rich Donnellan
Rich Donnellan
Treehouse Moderator 27,671 Points

You have an error in the foreach loop:

<li><?php echo $books . " (" . $isbn . ")"; ?></li>

$books is the array, and you want to echo out a single $book. I also find it easier to concatenate using the double quotes; much easier to read, IMO (and still passes the challenge). Anything variables inside are interpreted.

<li><?= "$var1 ($var2)"; ?></li> // using the echo shorthand (valid in PHP 5.4 and up)
Kerri-Ann Bates
Kerri-Ann Bates
15,422 Points

Aahhh right, the error is from $books. I missed that detail. Thank you! And also thanks for the tip using the echo shorthand.