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Upgrading to PHP 5 by Adam Trachtenberg

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SimpleXML Iterator

The SimpleXML iterator allows you to use SimpleXML objects with the other iterator classes. This allows you to easily construct an SQL-like interface to XML files.

For instance, suppose you have an XML address book like the one in Example 5-1. However, instead of containing only 2 records, it contains hundreds of records, and you want to display the records in groups of 10.

One solution is to place the information into a database. Another is to use XPath. A third is to combine a SimpleXMLIterator with a LimitIterator:

$ab = file_get_contents('address-book.xml');
$page = 0;
$limit = 10;

foreach (new LimitIterator(new SimpleXMLIterator($ab), 
            $page * $limit, $limit) as $person) {
    
    print "$person->firstname $person->lastname: $person->email\n";
}

The SimpleXMLIterator takes a string of XML and creates an iterable SimpleXML object. Here, it’s parsing address-book.xml.

This iterator is then passed to a LimitIterator that restricts the output to only the $limit number of records beginning at $page * $limit. When $page is 0, it returns the first 10 records; when $page is 1, you get records 11 through 20.

The $person item can be treated like a SimpleXMLElement, so $person->firstname returns the text stored in the firstname element.

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