If you want to use multiple libxml options, separate them with a pipe, like so:

The key is noted above example #6 here:
http://uk2.php.net/manual/en/simplexml.examples.php

"To compare an element or attribute with a string or pass it into a function that requires a string, you must cast it to a string using (string). Otherwise, PHP treats the element as an object."

If a tag contains CDATA, SimpleXML remembers that fact, by representing it separately from the string content of the element. So some functions, including print_r(), might not show what you expect. But if you explicitly cast to a string, you get the whole content.

<?php
$xml = simplexml_load_string('<foo>Text1 &amp; XML entities</foo>');
print_r($xml);
/*
SimpleXMLElement Object
(
    [0] => Text1 & XML entities
)
*/

$xml2 = simplexml_load_string('<foo><![CDATA[Text2 & raw data]]></foo>');
print_r($xml2);
/*
SimpleXMLElement Object
(
)
*/
// Where's my CDATA?

Here is the code of the function array2xml that I've developed to perform this conversion. Please note that this code is simple without any checks.

<?php
function array2xml($array, $tag) {

    function ia2xml($array) {
        $xml="";
        foreach ($array as $key=>$value) {
            if (is_array($value)) {
                $xml.="<$key>".ia2xml($value)."</$key>";
            } else {
                $xml.="<$key>".$value."</$key>";
            }
        }
        return $xml;
    }

    return simplexml_load_string("<$tag>".ia2xml($array)."</$tag>");
}

$test['type']='lunch';
$test['time']='12:30';
$test['menu']=array('entree'=>'salad', 'maincourse'=>'steak');

<?php

$xml = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<ns1:Root xmlns:ns1="http://example.com/custom">
<ns1:Node>There's stuff here</ns1:Node>
</ns1:Root>
XML;

$simplexml = simplexml_load_string($xml);

// This prints "Parse Error".
echo ($simplexml ? 'Valid XML' : 'Parse Error'), PHP_EOL;

// But this prints "There's stuff here", proving that
// the SimpleXML object was created successfully.
echo $simplexml->children('http://example.com/custom')->Node, PHP_EOL;

// Use this instead:
echo ($simplexml !== FALSE ? 'Valid XML' : 'Parse Error'), PHP_EOL;

?>

See:

simplexml_load_string has a problem with entities other than (&lt;, &gt;, &amp;, &quot; and &apos;).

<?php
class simple_xml_extended extends SimpleXMLElement
{
    public    function    Attribute($name)
    {
        foreach($this->Attributes() as $key=>$val)
        {
            if($key == $name)
                return (string)$val;
        }
    }

}

$xml = simplexml_load_string('
<xml>
  <dog type="poodle" owner="Mrs Smith">Rover</dog>
</xml>', 'simple_xml_extended');

echo $xml->dog->Attribute('type');

?>

outputs 'poodle'

<?php

// data in xml
$xml_txt = '
<root>
  <folder ID="65" active="1" permission="1"><![CDATA[aaaa]]></folder>
  <folder ID="65" active="1" permission="1"><![CDATA[bbbb]]></folder>
</root>';

// load xml into SimpleXML object
$xml = simplexml_load_string($xml_txt, 'SimpleXMLElement', LIBXML_NOCDATA);//LIBXML_NOCDATA LIBXML_NOWARNING

// see object structure
print_r($xml);

/* this prints
SimpleXMLElement Object
(
    [folder] => Array
        (
            [0] => aaaa
            [1] => bbbb
        )

)
*/

// but...
foreach ($xml->folder as $value){
    print_r($value);
}
/* prints complete structure of each folder element:
SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [ID] => 65
            [active] => 1
            [permission] => 1
        )

    [0] => aaaa
)

SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [ID] => 65
            [active] => 1
            [permission] => 1
        )

    [0] => bbbb
)

<?php simplexml_load_string('<?xml version="1.0" encoding="utf-8"?><xml/>'); ?>

The generated xml outputed by $xml->asXML will containt accentuated characters like 'é' instead of &#xE9;.

class.new.php
<?php
namespace foobar;

class new extends SimpleXMLElement
{
    public function do()
    {
        echo "done";
    }
}
?>

false.php
<?php
use foobarnew;

$result = simplexml_load_string($xml, 'new'); // it gives warning
$result->do(); // fatal error
?>

true.php
<?php
use foobarnew;
$result = simplexml_load_string($xml, 'foobarnew');

<?php
$xml = simplexml_load_string('<root><number>1</number></root>');
echo $xml->asXml(). "nn";

$xml->number->{0} = $xml->number->{0} + 1;

echo $xml->asXml();
?>

echos:
<?xml version="1.0"?>
<root><number>1</number></root>

<?xml version="1.0"?>
<root><number>2</number></root>

However, this only works with a direct assignment, not with any of the other operators:

<?php
$xml = simplexml_load_string('<root><number>1</number></root>');
echo $xml->asXml(). "nn";

$xml->number->{0} += 1;
// Or:
$xml->number->{0}++;

echo $xml->asXml();
?>

Both of the above cases would result in:

<?xml version="1.0"?>
<root><number>1</number></root>

For instance LIBXML_XINCLUDE does not work. But there is however a work around:

<?php
$xml = new DOMDocument();
$xml->loadXML ($XMLString);
           
$xml->xinclude();
$xml = simplexml_import_dom($xml);

when you have something like:

<?php
$xmlstr = <<<XML
<?xml version="1.0" encoding="utf-8"?>
<double xmlns="http://foosite.foo/">2328</double>
XML;
?>

you will have the simpleXML object "transformed" to the text() content:

<?php
$sx = simplexml_load_string('
<test>
<one>hi</one>
<two><![CDATA[stuff]]></two>
<t>
  <for>two</for>
</t>
<multi>one</multi>
<multi>two</multi>
</test>');
foreach((array) $sx as $tagname => $val) {
    if (is_string($val)) {
       // <one> will go here
    } elseif (is_array($val)) {
       // <multi> will go here because it happens multiple times
    } elseif (is_object($val)) {
      // <t> will go here because it contains tags
      // <two> will go here because it contains CDATA!
    }
}
?>

To test in the loop, do this