Working with XML in PHP

<?php
	//XMLwriter to write XML from scratch - Little complex example
	$xml = new XMLWriter();
	$xml->openMemory();
	$xml->startDocument();
		$xml->startElement("purchase");
			$xml->startElement("customer");							//Start of customer with id 1
				$xml->writeElement("id", 1);
				$xml->writeElement("time", "2013-04-19 10:56:03");
				$xml->writeElement("total", "$350");
			$xml->endElement();										//End of customer with id 1
			$xml->startElement("customer");							//Start of customer with id 2
				$xml->writeElement("id", 2);
				$xml->writeElement("time", "2013-04-23 13:43:41");
				$xml->writeElement("total", "$1456");
			$xml->endElement();										//End of customer with id 2
		$xml->endElement();
	$nXML =  $xml->outputMemory();							//Store the XML in $nXML
	
	/* 	XMLReader starts from here for Little Complex Example - XMLReader
		To get the total amount spent by custormer with id 1
	*/
	$rxml = new XMLReader();								//Create new XMLReader Object
	$rxml->xml($nXML);										//Load in the XML
	while($rxml->read() && $rxml->name !== 'customer');		//Move to the first customer child 
	
	$amountSpent = 0;
	while($rxml->name === 'customer')
	{														/* The child xml gotten using the readOuterXML() will look thus
																<customer><id>1</id><time>2013-04-19 10:56:03</time><total>$350</total></customer>
															*/
		$node = new SimpleXMLElement($rxml->readOuterXML());//Read the current child xml into a SimpleXMLElement
		if($node->id == 1)									//Check if the id node as 1 as it value
		{
			$amountSpent = $node->total;
			break;
		}
		$rxml->next('customer');							//Move to the next customer child
	}
	
	echo $amountSpent;
?>