<?php
//Creates XML string and XML document using the DOM
$dom = new DomDocument('1.0');
//add root - <books>
$books = $dom->appendChild($dom->createElement_x_x ('books'));
//add <book> element to <books>
$book = $books->appendChild($dom->createElement_x_x ('book'));
//add <title> element to <book>
$title = $book->appendChild($dom->createElement_x_x ('title'));
//add <title> text node element to <title>
$title->appendChild($dom->createTextNode('Great American Novel'));
//generate xml
$dom->formatOutput = true; // set the formatOutput attribute of domDocument to true
//save XML as string or file
$test1 = $dom->saveXML(); // put string in test1
$dom -> save('test1.xml'); // save as file
?>

$aa = "111";
$xmlstr = <<<XML
<?xml version='1.0'?>
<document>
<title>{$aa}</title>
<from>Joe</from>
<to>Jane</to>
<body>
I know that's the answer -- but what's the question?
</body>
</document>
XML;
$dom = new domDocument;
$dom->loadXML($xmlstr);
$test1 = $dom->saveXML();
$dom->save('test1.xml');

<?xml version="1.0"?>
<books>
<book>
<author>Jack Herrington</author>
<title>PHP Hacks</title>
<publisher>O'Reilly</publisher>
</book>
<book>
<author>Jack Herrington</author>
<title>Podcasting Hacks</title>
<publisher>O'Reilly</publisher>
</book>
</books>

$doc = new DOMDocument();
$doc->load('test1.xml');
$books = $doc->getElementsByTagName("book");
foreach($books as $book){
$authors = $book->getElementsByTagName("author");
$author = $authors->item(0)->nodeValue;
$publishers = $book->getElementsByTagName( "publisher" );
$publisher = $publishers->item(0)->nodeValue;
$titles = $book->getElementsByTagName( "title" );
$title = $titles->item(0)->nodeValue;
echo "$title - $author - $publisher\n";
}

<?
$xmlstr = <<<XML
<?xml version='1.0' standalone='yes'?>
<books>
<book>
<title>Great American Novel</title>
<characters>
<character>
<name>Cliff</name>
<desc>really great guy</desc>
</character>
<character>
<name>Lovely Woman</name>
<desc>matchless beauty</desc>
</character>
<character>
<name>Loyal Dog</name>
<desc>sleepy</desc>
</character>
</characters>
<plot>
Cliff meets Lovely Woman. Loyal Dog sleeps, but wakes up to bark
at mailman.
</plot>
<success type='bestseller'>4</success>
<success type='bookclubs'>9</success>
</book>
</books>
XML;

//提取节点内容
$xml = new SimpleXMLElement($xmlstr);
foreach ($xml->book[0]->success as $success) {
switch((string) $success['type']) { // Get attributes as element indices
case 'bestseller':
echo $success. ' months on bestseller list<br>';
break;
case 'bookclubs':
echo $success. ' bookclub listings';
break;
}
}

//修改文本节点内容
$xml = new SimpleXMLElement($xmlstr);
$xml->book[0]->characters->character[0]->name = 'Big Cliff';
echo $xml->asXML();

//添加子元素的文本节点
$xml = new SimpleXMLElement($xmlstr);
$character = $xml->book[0]->characters->addChild('character');
$character->addChild('name', 'Yellow Cat');
$character->addChild('desc', 'aloof');
$success = $xml->book[0]->addChild('success', '2');
$success->addAttribute('type', 'reprints');
echo $xml->asXML();

?>

if (file_exists('test1.xml')) { //读取xml文件
$xml = simplexml_load_file('test1.xml');
var_dump(xml);
} else {
exit('Failed to open test1.xml.');
}

<?php
$sxe = simplexml_load_string('<books><book><title>Great American
Novel</title></book></books>');
if ($sxe === false) {
echo 'Error while parsing the document';
exit;
}
$dom_sxe = dom_import_simplexml($sxe);
if (!$dom_sxe) {
echo 'Error while converting XML';
exit;
}
$dom = new DOMDocument('1.0');
$dom_sxe = $dom->importNode($dom_sxe, true);
$dom_sxe = $dom->appendChild($dom_sxe);
$test2 = $dom->saveXML(); // put string in test2
$dom -> save('test2.xml'); // save as file
?>

<?php
$dom = new domDocument;
$dom->loadXML('<books><book><title>Great American
Novel</title></book></books>');
if (!$dom) {
echo 'Error while parsing the document';
exit;
}
$s = simplexml_import_dom($dom);
echo $s->book[0]->title; // Great American Novel
?>