SimpleXML 函数
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simplexml_load_string

(PHP 5)

simplexml_load_string — Interprets a string of XML into an object

说明

SimpleXMLElement simplexml_load_string ( string $data [, string $class_name = "SimpleXMLElement" [, int $options = 0 [, string $ns = "" [, bool $is_prefix = false ]]]] )

Takes a well-formed XML string and returns it as an object.

参数

data

A well-formed XML string

class_name

You may use this optional parameter so that simplexml_load_string() will return an object of the specified class. That class should extend the SimpleXMLElement class.

options

Since PHP 5.1.0 and Libxml 2.6.0, you may also use the options parameter to specify additional Libxml parameters.

ns

Namespace prefix or URI.

is_prefix

TRUE if ns is a prefix, FALSE if it's a URI; defaults to FALSE.

返回值

Returns an object of class SimpleXMLElement with properties containing the data held within the xml document, 或者在失败时返回 FALSE.

错误/异常

Produces an E_WARNING error message for each error found in the XML data.

Tip

Use libxml_use_internal_errors() to suppress all XML errors, and libxml_get_errors() to iterate over them afterwards.

范例

Example #1 Interpret an XML string

<?php
$string = <<<XML
<?xml version='1.0'?> 
<document>
 <title>Forty What?</title>
 <from>Joe</from>
 <to>Jane</to>
 <body>
  I know that's the answer -- but what's the question?
 </body>
</document>
XML;

$xml = simplexml_load_string($string);

print_r($xml);
?>

以上例程会输出：

SimpleXMLElement Object
(
  [title] => Forty What?
  [from] => Joe
  [to] => Jane
  [body] =>
   I know that's the answer -- but what's the question?
)

At this point, you can go about using $xml->body and such.

参见

SimpleXML 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Interprets a string of XML into an object

用户评论:

Anonymous (01-Mar-2012 04:54)

Use libxml_disable_entity_loader() to restrict loading of external files.  See http://www.idontplaydarts.com/2011/02/scanning-the-internal-network-using-simplexml/

chris at willowsconsulting dot ie (15-Nov-2011 12:20)

There is NO NEED to convert to an array, an Object is more powerful than an array...

To access the data, simply do (using the example set above):

<?php

echo $xml->title;
echo $xml->from;
// etc to access the relevant data~~

?>

lb at bostontech dot net (08-Nov-2011 06:40)

please note that:

<?
$data_array = (array) simplexml_load_string($xml_string);
?>

will only convert the root element to an array, where as the child elements remain XML objects.

To prove this, try returning a value N objects deep by association.  Then try the same exercise using something like the object2array example below. (Which works great).

tomas at rds dot lt (13-Sep-2011 04:57)

The most simple way to get assoc array from xml string:
<?
$data_array = (array) simplexml_load_string($xml_string);
?>

Diego Araos, diego at klapmedia dot com (05-Feb-2011 08:57)

A simpler way to transform the result into an array (requires json module).

<?php
function object2array($object) { return @json_decode(@json_encode($object),1); }
?>

Example:
<?php
$xml_object=simplexml_load_string('<SOME XML DATA');
$xml_array=object2array($xml_object);
?>

ascammon at hotmail dot com (28-Dec-2010 09:04)

I had a hard time finding this documented, so posting it here in case it helps someone:

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

<?php
$xml = simplexml_load_string($string, 'SimpleXMLElement', LIBXML_NOCDATA | LIBXML_NOBLANKS);
?>

thejhereg at gmail dot com (30-Aug-2010 07:24)

"simplexml_load_string() : Entity: line #: parser error : Comment not terminated"

On the off chance you see this error and you're pulling your hair out over it, simplexml can't seem to correctly parse XML comment tags if the comment contains "--".

Is silly and likely won't happen very often -- but sometimes it does. ;-)

jeff at creabilis dot com (17-Nov-2009 10:28)

If you want to set the charset of the outputed xml, simply set the encoding attribute like this :

<?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;.

Hope this help

spcmky at gmail dot com (13-Oct-2009 09:50)

Most of the xml 2 array functions listed here fail when they encounter the following xml:

<something code="231" type="open">Value</something>

The attributes get dropped.

Bob (17-Jun-2009 10:16)

Here is my simple SimpleXML wrapper function.
As far as I can tell, it does the same as Julio Cesar Oliveira's (above).
It parses an XML string into a multi-dimensional associative array.
The second argument is a callback that is run on all data (so for example, if you want all data trimmed, like Julio does in his function, just pass 'trim' as the second arg).
<?php
function unserialize_xml($input, $callback = null, $recurse = false)
/* bool/array unserialize_xml ( string $input [ , callback $callback ] )
 * Unserializes an XML string, returning a multi-dimensional associative array, optionally runs a callback on all non-array data
 * Returns false on all failure
 * Notes:
    * Root XML tags are stripped
    * Due to its recursive nature, unserialize_xml() will also support SimpleXMLElement objects and arrays as input
    * Uses simplexml_load_string() for XML parsing, see SimpleXML documentation for more info
 */
{
    // Get input, loading an xml string with simplexml if its the top level of recursion
    $data = ((!$recurse) && is_string($input))? simplexml_load_string($input): $input;
    // Convert SimpleXMLElements to array
    if ($data instanceof SimpleXMLElement) $data = (array) $data;
    // Recurse into arrays
    if (is_array($data)) foreach ($data as &$item) $item = unserialize_xml($item, $callback, true);
    // Run callback and return
    return (!is_array($data) && is_callable($callback))? call_user_func($callback, $data): $data;
}
?>

tiznull (07-Apr-2009 06:16)

SimpleXMLElement - Warning: unserialize() [function.unserialize]: Node no longer exists in … .php

If you get this error from storing serialized SimpleXMLElement data then this is your fix…

<?php

function sxml_unserialze($str) {
return unserialize(str_replace(array('O:16:"SimpleXMLElement":0:{}', 'O:16:"SimpleXMLElement":'), array('s:0:"";', 'O:8:"stdClass":'), $str));
}

?>

Julio Cesar Oliveira (30-Mar-2009 03:14)

The XML2Array func now Recursive!

<?php
function XML2Array ( $xml , $recursive = false )
{
    if ( ! $recursive )
    {
        $array = simplexml_load_string ( $xml ) ;
    }
    else
    {
        $array = $xml ;
    }
   
    $newArray = array () ;
    $array = ( array ) $array ;
    foreach ( $array as $key => $value )
    {
        $value = ( array ) $value ;
        if ( isset ( $value [ 0 ] ) )
        {
            $newArray [ $key ] = trim ( $value [ 0 ] ) ;
        }
        else
        {
            $newArray [ $key ] = XML2Array ( $value , true ) ;
        }
    }
    return $newArray ;
}
?>

Julio Cesar Oliveira (26-Mar-2009 04:57)

<?php
function XML2Array ( $xml )
{
    $array = simplexml_load_string ( $xml );
    $newArray = array ( ) ;
    $array = ( array ) $array ;
    foreach ( $array as $key => $value )
    {
        $value = ( array ) $value ;
        $newArray [ $key] = $value [ 0 ] ;
    }
    $newArray = array_map("trim", $newArray);
  return $newArray ;
}
?>

supzero at phparts dot net (07-Mar-2009 06:04)

if we don't know children number. How many loop. How many key.

<?php
class XML {
    protected $pointer;
    public    $degerler=array();
   
    function loadString($string){
        $this->pointer = simplexml_load_string($string);
                return $this->pointer;
    }
   
    function loadFile($file){
        $this->pointer = simplexml_load_file($file);
        return $this->pointer;
    }
   
    function getname(){
        return $this->pointer->getName();
    }
    function child(){
        return $this->pointer->children();
    }
    function att(){
        return $this->pointer->attributes();
    }
    function toArray(){
        foreach ($this->child() as $sq){
            $this->degerler[$this->getname()][$sq->getname()][][] = $sq; // How many key
        }
        return;
    }
   
}
?>

Mark Omohundro, ajamyajax.com (04-Nov-2008 06:33)

How about a recursive function to reduce the xml hard-coding in your apps?  Here is my simple listing routine as an example:

<?php
function list_xml($str) {
  $root = simplexml_load_string($str);
  list_node($root);
}

function list_node($node) {
  foreach ($node as $element) {
    echo $element. "\n";
    if ($element->children()) {
      echo "<br/>";
      list_node($element);
    }
  }
}
?>

javalc6 at gmail dot com (18-Oct-2008 02:25)

I wanted to convert an array containing strings and other arrays of the same type into a simplexml object.

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');

echo array2xml($test,"meal")->asXML();
?>

rowan dot collins at gmail dot com (10-Jul-2008 03:07)

There seems to be a lot of talk about SimpleXML having a "problem" with CDATA, and writing functions to rip it out, etc. I thought so too, at first, but it's actually behaving just fine under PHP 5.2.6

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?

// Let's try explicit casts
print_r( (string)$xml );
print_r( (string)$xml2 );
/*
Text1 & XML entities
Text2 & raw data
*/
// Much better
?>

SmartD (11-Jun-2008 04:40)

A small 'n nice function to extract an XML and return it as an array. If there is a bug, please let me know here. I testet it for my purposes and it works.

<?php

public function extractXML($xml) {
       
if (!($xml->children())) {
    return (string) $xml;
}
       
foreach ($xml->children() as $child) {
    $name=$child->getName();
    if (count($xml->$name)==1) {
        $element[$name] = $this->extractXML($child);
    } else {
        $element[][$name] = $this->extractXML($child);
    }
}

return $element;   
}

// you can call it this way

$xml = false;

$xml = @simplexml_load_string($xmlstring);

// 1)

if ($xml) {
  $array = extractXML($xml);
}  else {
  $array = false;
}

// 2)

if ($xml) {
  $array[$xml->getName()] = extractXML($xml);
}  else {
  $array = false;
}

?>

nospam at qool dot com (05-Jun-2008 07:45)

simplexml doesn't appear to like long attributes. I have tried passing it a valid xhtml document but the url in the anchor tag was causing simplexml to generate an error.

kyle at codeincarnate dot com (22-Apr-2008 01:28)

A looked through a lot of the sample code for reading XML files with CDATA, but they didn't work out that well for me.  However, I found that the following piece of code worked perfectly for reading through a file using lots of CDATA.

<?php
$article_string = file_get_contents($path);
$article_string = preg_replace_callback('/<!\[CDATA\[(.*)\]\]>/', 'filter_xml', $article_string);
$article_xml = simplexml_load_string($article_string); 

function filter_xml($matches) {
    return trim(htmlspecialchars($matches[1]));
}

?>

paulyg76 at NOSPAM dot gmail dot com (19-Feb-2008 02:39)

Be careful using nested SimpleXML objects in double quoted strings.

<?php
$xmlstring = '<root><node>123</node><foo><bar>456</bar></foo></root>';

$root = simplexml_load_string($xmlstring);

echo "Node is: $root->node"; // Works: Node is 123
echo "Bar is: $root->foo->bar"; // Doesn't work, outputs: Bar is: ->bar
// use curly brackets to fix
echo "Bar is: {$root->foo->bar}"; // Works: Bar is 456

?>

amir_abiri at ipcmedia dot com (08-Feb-2008 04:47)

It doesn't seem to be documented anywhere, but you can refer to an element "value" for the purpose of changing it like so:

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

$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(). "\n\n";

$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>

<?xml version="1.0"?>
<root><number>1<0/></number></root>

bojan (04-Feb-2008 12:38)

As was said before don't use var_dump() or print_r() to see SimpleXML object structure as they do not returns always what you expect.
Consider the following:

<?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
)

*/
?>

hattori at hanso dot com (15-Oct-2007 11:19)

Theres a problem with the below workaround when serializing fields containing html CDATA. For any other content type then HTML try to modfiy function parseCDATA.
Just add these lines before serializing.
This is also a workaround for this bug http://bugs.php.net/bug.php?id=42001

<?PHP
if(strpos($content, '<![CDATA[')) {
   function parseCDATA($data) {
      return htmlentities($data[1]);
   }
   $content = preg_replace_callback(
      '#<!\[CDATA\[(.*)\]\]>#',
      'parseCDATA',
      str_replace("\n", " ", $content)
   );
}
?>

hattori at hanso dot com (17-Sep-2007 10:15)

If you want to serialize and unserialize SimpleXMLElement objects for caching, you need to transform the SimpleXMLElement object into a standard class object before unserializing.
This is only if you want to cache converted data, the functionallity of the SimpleXMLElement will not be held.

$content = '<SomeXML....'

$serialized = str_replace(
  array('O:16:"SimpleXMLElement":0:{}', 'O:16:"SimpleXMLElement":'),
  array('s:0:"";', 'O:8:"stdClass":'),
  serialize(simplexml_load_string($content))
);

$unserialized = unserialize($serialized);

nbijnens at servs dot eu (10-Sep-2007 01:17)

Please note that not all LIBXML options are supported with the options argument.

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);

?>

Pedro (06-Jul-2007 09:28)

Attention:

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

Use numeric character references instead!

youx_free_fr (23-May-2007 05:52)

While needing to add an xml subtree to an existing simplexml object, I noticed that simplexml_load_string fails with strings like
<emptynode></emptynode>

I needed to use dom instead of simplexml to bypass this problem and work with any kind of xml strings.

David Somerset (08-May-2007 07:39)

Another option for having simplexml convert CDATA into plain text is to simply type cast the result to string. Here's an example:

$xmlRoot = simplexml_load_string('<?xml version="1.0"?>

<tvshows>
    <show>
        <name>The Simpsons</name>
    </show>
     <show>
        <name><![CDATA[Lois & Clark]]></name>
    </show>
</tvshows>');

$show = array();

foreach($xmlRoot as $val){
    $show[] = (string) $val->name;
    }

php at teamhirsch dot com (24-Apr-2007 10:46)

It's worth noting that in the example above, $xml->body will actually return an object of type SimpleXMLElement, not a string, e.g.

 SimpleXMLElement Object (
       [0] => this is the text in the body tag
  ) 

If you want to get a string out of it you must explicitly cast it using (string) or double quotes, or pass $xml->body (or whatever attribute you want to access) to any function that returns a string, such as urldecode() or trim().

m dot ament at mailcity dot com (06-Mar-2007 02:51)

Warning:

The parsing of XML-data will stop when reaching character 0.
Please avoid this character in your XML-data.

mindpower (30-Jan-2007 11:03)

A simple extension that adds a method for retrieving a specific attribute:

<?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'

I prefer to use this technique rather than typecasting attributes.

h (15-Nov-2006 06:44)

seems like simplexml has a line-length restriction - fails if a largeish XML doc with no linebreaks is passed as a string or file.

h

roy dot walter at nospam dot brookhouse dot co dot uk (16-Oct-2006 05:15)

simplexml provides a neat way to do 'ini' files. Preferences for any number of users can be held in a single XML file having elements for each user name with user specific preferences as attributes of child elements. The separate <pref/>'s could of course be combined as multiple attributes of a single <pref/> element but this could get unwieldy.

In the sample code below the makeXML() function uses the simplexml_load_string function to generate some XML to play with and the readPrefs() function parses the requested users preferences into an array.

<?php
function makeXML() {

$xmlString = <<<XML
<preferences>
    <johndoe>
        <pref color="#FFFFFF"/>
        <pref size="14"/>
        <pref font="Verdana"/>
    </johndoe>
    <janedoe>
        <pref color="#000000"/>
        <pref size="16"/>
        <pref font="Georgia"/>
    </janedoe>   
</preferences>
XML;

return simplexml_load_string($xmlString);

}
function readPrefs($user, $xml) {
   
    foreach($xml->$user as $arr);
        $n = count($arr);
           
    for($i=0;$i<$n;$i++) {
        foreach($xml->$user->pref[$i]->attributes() as $a=>$b) {
            $prefs[$a] = (string)$b;
        }
    }
       
    print_r($prefs);
}

readPrefs('johndoe', makeXML());

?>

paul at santasoft dot com (25-Jul-2006 04:22)

If you have PHP > 5.1 and LibXML > 2.6, use this function call to have simplexml convert CDATA into plain text.

simplexml_load_string($xmlstring, 'SimpleXMLElement', LIBXML_NOCDATA);

Too bad, so sad with PHP < 5.1.

lists at cyberlot dot net (07-Sep-2005 08:51)

While you can't add new elements to a SimpleXML object you can however add new attributes
<?php
$string = '<doc channel="chat"><test1>Hello</test1></doc>';
$xml = simplexml_load_string($string);
$xml->test1['sub'] = 'No';
echo $xml->asXML();
?>

Will return output
<doc channel="chat"><test1 sub="No">Hello</test1></doc>

Maciek Ruckgaber <maciekrb at gmai dot com> (08-Jun-2005 01:07)

after wondering around some time, i just realized something (maybe obvious, not very much for me). Hope helps someone to not waste time as i did :-P

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
$xml = simplexml_load_string($xmlstr);
echo $xml; // this will echo 2328  (string)
?>

igor kraus (07-Jan-2005 06:37)

A simple way to merge two SimpleXML objects.

<?php
/**
* Pumps all child elements of second SimpleXML object into first one.
*
* @param    object      $xml1   SimpleXML object
* @param    object      $xml2   SimpleXML object
* @return   void
*/
function simplexml_merge (SimpleXMLElement &$xml1, SimpleXMLElement $xml2)
{
    // convert SimpleXML objects into DOM ones
    $dom1 = new DomDocument();
    $dom2 = new DomDocument();
    $dom1->loadXML($xml1->asXML());
    $dom2->loadXML($xml2->asXML());

    // pull all child elements of second XML
    $xpath = new domXPath($dom2);
    $xpathQuery = $xpath->query('/*/*');
    for ($i = 0; $i < $xpathQuery->length; $i++)
    {
        // and pump them into first one
        $dom1->documentElement->appendChild(
            $dom1->importNode($xpathQuery->item($i), true));
    }
    $xml1 = simplexml_import_dom($dom1);
}

$xml1 = simplexml_load_string('<root><child>child 1</child></root>');
$xml2 = simplexml_load_string('<root><child>child 2</child></root>');
simplexml_merge($xml1, $xml2);
echo($xml1->asXml());
?>

Will output:
<?xml version="1.0"?>
<root>
    <child>child 1</child>
    <child>child 2</child>
</root>

cellog at php dot net (01-Sep-2004 12:11)

simplexml does not simply handle CDATA sections in a foreach loop.

<?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

<?php
if (count((array) $val) == 0) {
    // this is not a tag that contains other tags
    $val = '' . $val;
    // now the CDATA is revealed magically.
}
?>

greg dot steffensen at spamless dot richmond dot edu (19-Feb-2004 11:04)

Simplexml's simplicity can be deceptive.  Simplexml elements behave either as objects or strings, depending on the context in which they're used (through overloading of the __toString() method, I assume).  Statements implying conversion to string treat them as strings, while assignment operations treat them as objects.  This can lead to unexpected behavior if, for example, you are trying to compare the values of two Simplexml elements.  The expected syntax will not work.  To force conversion to strings, just "typecast' whatever Simplexml element you're using.  For example:

<?php
$s = simplexml_load_string('<foo>43</foo> <bar>43</bar>');

// Evaluates to false by comparing object IDs instead of strings
($s->foo == $s->bar);

// Evaluates to true
((string)$s->foo == (string)$s->bar);
?>

[Ed. Note: Changed from quotes to casts because casts provide a quicker and more explicit conversion than do double quotes.]