php Crawl XML phrases

I Have This Xml File

<?xml version="1.0" encoding="UTF-8"?>
<library>
    <book id="1">
        <title>PHP and MySQL</title>
        <author id="test">Miguel Alvarez</author>
        <publisher>WebHole</publisher>
        <price>1.99</price>
    </book>
    <book id="2">
        <title>JAVA 123</title>
        <author id="test2">WIlliam Vega</author>
        <publisher>WebHole</publisher>
        <price>2.99</price>
    </book>
</library>

Code (markup):

And This PHP file

 <?php
$url = "test.xml";
$xml = simplexml_load_file($url);
foreach ($xml->book as $entry){
echo $entry->author . ' <br />';
}
?>

PHP:

It'll show
Miguel Alvarez
WIlliam Vega

how can I get only Miguel Alvarez as result, Like foreach ($xml->book['id=1'] as $entry)
Or echo $entry->author['id=test'] . ' <br />';

Please help me

 

You probably want to look at using SimpleXMLElement::xpath to accomplish that.

http://php.net/manual/en/simplexmlelement.xpath.php

Or you could always just stick some if() logic inside your foreach().

 

you could put an extra value into each book like an ISBN and then use

if ($entry->isbn == '1')
{
}

 

For xml / html parsing with PHP - 'QueryPath' is your best bet.