ZEND PHP 5 Certification STUDY GUIDE

194 ” XML and Web Services
What this example doesn’t show is that you may also iterate through the the children
and attributes of $subchild and so forth using either a recursive function or an iterator
(explained in the Design and Theory chapter), it is possible to access every single
child and attribute at every depth of the XML document.
XPath Queries
The XML Path Language (XPath) is a W3C standardized language that is used to access
and search XML documents. It is used extensively in Extensible Stylesheet Language
Transformations (XSLT) and forms the basis of XML Query (XQuery) and XML
Pointer (XPointer). Think of it as a query language for retrieving data from an XML
document. XPath can be a very complex language, and with this complexity comes
a lot of power, which SimpleXML leverages with the SimpleXMLElement::xpath()
method.
Using SimpleXMLElement::xpath(), you can run an Xpath query on any
SimpleXMLElement object. If used on the root element, it will search the entire XML
document. If used on a child, it will search the child and any children it may have.
The following illustrates an XPath query on both the root element and a child node.
XPath returns an array of SimpleXMLElement objects—even if only a single element is
returned.
// Search the root element
$results = $library->xpath(’/library/book/title’);
foreach ($results as $title)
{
echo $title . "\n";
}
// Search the first child element
$results = $library->book[0]->xpath(’title’);
foreach ($results as $title)
{
echo $title . "\n";
}
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)