参见https://github.com/gaarf/XML-string-to-PHP-array/blob/master/xmlstr_to_array.php

<?php
/**
  * convert xml string to php array - useful to get a serializable value
  *
  * @param string $xmlstr
  * @return array
  *
  * @author Adrien aka Gaarf & contributors
  * @see http://gaarf.info/2009/08/13/xml-string-to-php-array/
*/
function xmlstr_to_array($xmlstr) {
  $doc = new DOMDocument();
  $doc->loadXML($xmlstr);
  $root = $doc->documentElement;
  $output = domnode_to_array($root);
  $output['@root'] = $root->tagName;
  return $output;
}
function domnode_to_array($node) {
  $output = array();
  switch ($node->nodeType) {
    case XML_CDATA_SECTION_NODE:
    case XML_TEXT_NODE:
      $output = trim($node->textContent);
    break;
    case XML_ELEMENT_NODE:
      for ($i=0, $m=$node->childNodes->length; $i<$m; $i++) {
        $child = $node->childNodes->item($i);
        $v = domnode_to_array($child);
        if(isset($child->tagName)) {
          $t = $child->tagName;
          if(!isset($output[$t])) {
            $output[$t] = array();
          }
          $output[$t][] = $v;
        }
        elseif($v || $v === '0') {
          $output = (string) $v;
        }
      }
      if($node->attributes->length && !is_array($output)) { //Has attributes but isn't an array
        $output = array('@content'=>$output); //Change output into an array.
      }
      if(is_array($output)) {
        if($node->attributes->length) {
          $a = array();
          foreach($node->attributes as $attrName => $attrNode) {
            $a[$attrName] = (string) $attrNode->value;
          }
          $output['@attributes'] = $a;
        }
        foreach ($output as $t => $v) {
          if(is_array($v) && count($v)==1 && $t!='@attributes') {
            $output[$t] = $v[0];
          }
        }
      }
    break;
  }
  return $output;
}

我喜欢这个问题，一些答案对我很有帮助，但我需要将xml转换为一个支配数组，所以我将发布我的解决方案，也许以后有人需要它:

<?php
$xml = json_decode(json_encode((array)simplexml_load_string($xml)),1);
$finalItem = getChild($xml);
var_dump($finalItem);

function getChild($xml, $finalItem = []){
    foreach($xml as $key=>$value){
        if(!is_array($value)){
            $finalItem[$key] = $value;
        }else{
            $finalItem = getChild($value, $finalItem);
        }
    }
    return $finalItem;
}
?>  

我知道我晚了10亿年，但我遇到了和您一样的问题，需要一个更复杂的解决方案，因此我制作了一个函数(xml_decode())，将SimpleXMLElements转换为PHP数组，同时不丢失属性，并带有参数，以便更可定制地使用。

val()函数用于自定义如何处理元素值——例如，如果您想将<elem>true</elem>转换为true而不是“true”。

免责声明:我知道只使用PHP SimpleXML扩展更容易，但我需要将许多XML文件转换为JSON文件，以便在我的一个项目中进行重大更改。此外，这个问题是关于如何将XML转换为PHP数组，而不是如何在PHP中使用XML。

<?php

function val($input) {
    return strval($input);
}

/**
 * Transform an SimpleXMLElement into an associative array.
 * 
 * @param SimpleXMLElement $xml The XML element to be decoded.
 * 
 * @param bool $attributes_key If the element attributes should be grouped into a single element.
 * 
 * Example: <elem foo="true" bar="false" />
 * 
 * If true, xml_decode() will output
 * array("attributes" => array("foo" => "true", "bar" => "false"))
 * 
 * If false, xml_decode() will output
 * array("foo" => "true", "bar" => "false")
 * 
 * @param bool $reduce If unecessary keys created due to XML structure should be eliminated.
 * 
 * Example: <fruits><fruit>apple</fruit><fruit>banana</fruit></fruits>
 * 
 * If true, xml_decode() will output the element as
 * array("fruits" => array(0 => "apple", 1 => "banana"))
 * 
 * If false, xml_decode() will output the element as
 * array("fruits" => array("fruit" => array(0 => "apple", 1 => "banana")))
 * 
 * @param array $always_array List of which childs should be treated aways as an array.
 * 
 * Example: <fruits><fruit>apple</fruit></fruits>
 * 
 * If array("fruit") is passed as $aways_array, xml_decode() will output the element as
 * array("fruits" => array("fruit" => array(0 => "apple")))
 * 
 * If not, xml_decode() will output the element as
 * array("fruits" => array("fruit" => "apple"))
 * 
 * @param array $value_keys List of custom element's value names. This argument is only
 * used when values need to passed as elements because of attributes or other reasons.
 * 
 * The default value key name is "value".
 * 
 * Example: <fruits><fruit id="123">apple</fruit></fruits>
 * 
 * If array("fruit" => "name) is passed as $value_keys, xml_decode() will output the element as
 * array("fruits" => array("fruit" => array("attributes" => array("id" => "123"), "name" => "apple")))
 * 
 * If not, xml_decode() will output the element as
 * array("fruits" => array("fruit" => array("attributes" => array("id" => "123"), "value" => "apple")))
 */
function xml_decode(SimpleXMLElement $xml, bool $attributes_key = true, bool $reduce = true,
    array $always_array = array(), array $value_keys = array()): string|array {

    // Inicialize the array.
    $arr = array();

    // XML tag name.
    $xml_name = $xml->getName();

    // Turn attributes into elements.
    foreach ($xml->attributes() as $key => $value) {
        // Use a key for attributes if $attributes_key argument is true.
        if ($attributes_key) {
            $arr['attributes'][val($key)] = val($value);
        } else {
            $arr[val($key)] = val($value);
        }
    }

    // Count children.
    $children_count = $xml->children()->count();

    // No children? Value will be text.
    if ($children_count == 0) {

        // If attributes were found and turned into elements
        // the value shall be an element.
        if (count($arr) > 0) {
            // If attributes were found previosly.
            $key = $value_keys[$xml_name] ?? $value_keys['*'] ?? "value";
            $arr[$key] = val($xml);
        // Else, no need for an array.
        } else {
            $arr = val($xml);
        }

    // Children? Loop continues.
    } else {

        // Defines if there are unecessary array keys - due to the XML structure - to be cut.
        // Example: <fruits><fruit /><fruit /><fruits />
        // could be turned into arr['fruits'][0] and arr['fruits'][1] instead of
        // arr['fruits']['fruit'][0] and arr['fruits']['fruit'][1] for a
        // cleaner organization.
        $children_names = array();
        foreach ($xml->children() as $child) {
            $child_name = $child->getName();
            in_array($child_name, $children_names) or $children_names[] = $child_name;
        }
        $reducible = empty($arr) && count($children_names) === 1;

        foreach ($xml->children() as $child) {

            // Child's name shall be the element key.
            $name = $child->getName();
            
            // Children with the same name will be turned into a list.
            // Example: $arr['repeating-child'][...] = $value;
            if ($xml->$name->count() > 1 || in_array($name, $always_array)) {

                // Reduction, if possible and requested by the $reduce argument.
                if ($reduce && $reducible) {
                    $arr[] = xml_decode($child, $attributes_key, $reduce, $always_array, $value_keys);
                } else {
                    $arr[$name][] = xml_decode($child, $attributes_key, $reduce, $always_array, $value_keys);
                }

            // Normal children will be normally decoded.
            // Example: $arr['no-repeating-child] = $value;
            } else {
                
                $arr[$name] = xml_decode($child, $attributes_key, $reduce, $always_array, $value_keys);

            }
        }
    }

    return $arr;

}

恢复所有文档和注释，函数将属性和元素值转换为简单的数组元素，并使用自身的循环来处理包含子元素的元素。

这些参数允许你:

将属性分组为单独的键; 删除由于XML结构转换而产生的不必要的键(例如:fruits->fruit to $arr['fruits']['fruit'][n]); 设置应该被视为列表的元素(因为有时它只有一个子元素，但你仍然需要它是一个列表); 为数组元素键设置一个名称，它将表示XML元素文本值——当属性转换为数组元素时将需要这个值。

XML元素的使用示例(我认为你在11年后已经解决了这个问题，但我正在回答这个问题，所以……):

test.xml

<test>
    <aaaa Version="1.0">
        <bbb>
            <cccc>
                <dddd Id="id:pass" />
                <eeee name="hearaman" age="24" />
            </cccc>
        </bbb>
    </aaaa>
</test>

PHP

$xml = simplexml_load_file("test.xml");
$decode = xml_decode($xml);
echo "<pre>" . print_r($decode,true) . "</pre>";

输出

Array
(
    [aaaa] => Array
        (
            [attributes] => Array
                (
                    [Version] => 1.0
                )

            [bbb] => Array
                (
                    [cccc] => Array
                        (
                            [dddd] => Array
                                (
                                    [attributes] => Array
                                        (
                                            [Id] => id:pass
                                        )

                                    [value] => 
                                )

                            [eeee] => Array
                                (
                                    [attributes] => Array
                                        (
                                            [name] => hearaman
                                            [age] => 24
                                        )

                                    [value] => 
                                )

                        )

                )

        )

)

将一个XML字符串($buffer)转换为一个忽略属性的简化数组，并将具有相同名称的子元素分组:

function XML2Array(SimpleXMLElement $parent)
{
    $array = array();

    foreach ($parent as $name => $element) {
        ($node = & $array[$name])
            && (1 === count($node) ? $node = array($node) : 1)
            && $node = & $node[];

        $node = $element->count() ? XML2Array($element) : trim($element);
    }

    return $array;
}

$xml   = simplexml_load_string($buffer);
$array = XML2Array($xml);
$array = array($xml->getName() => $array);

结果:

Array
(
    [aaaa] => Array
        (
            [bbb] => Array
                (
                    [cccc] => Array
                        (
                            [dddd] => 
                            [eeee] => 
                        )

                )

        )

)

如果您还想拥有这些属性，可以通过SimpleXMLElement的JSON编码/解码使用它们。这通常是最简单快捷的解决方法:

$xml   = simplexml_load_string($buffer);
$array = json_decode(json_encode((array) $xml), true);
$array = array($xml->getName() => $array);

结果:

Array
(
    [aaaa] => Array
        (
            [@attributes] => Array
                (
                    [Version] => 1.0
                )

            [bbb] => Array
                (
                    [cccc] => Array
                        (
                            [dddd] => Array
                                (
                                    [@attributes] => Array
                                        (
                                            [Id] => id:pass
                                        )

                                )

                            [eeee] => Array
                                (
                                    [@attributes] => Array
                                        (
                                            [name] => hearaman
                                            [age] => 24
                                        )

                                )

                        )

                )

        )

)

请注意，所有这些方法都只能在XML文档的名称空间中工作。

两行代码(https://www.php.net/manual/en/book.simplexml.php#113485)

$xml = new SimpleXMLElement("<your><xml><string>ok</string></xml></your>");
$array = (array)$xml;

$array = json_decode(json_encode((array)simplexml_load_string($xml)),true);