多分これ:
<?php
$string = '<Parent>
<Children>
<child1>1</child1>
<secondchild>2</secondchild>
<child3>3</child3>
<fourth>4</fourth>
</Children>
</Parent>';
$xml = new SimpleXMLElement($string);
$children = $xml->xpath('/Parent/Children/*');
foreach ($children as $child){
echo $child->getName() . "\n";
}
また
<?php
$string = '<Parent>
<Children>
<child1>1</child1>
<secondchild>2</secondchild>
<child3>3</child3>
<fourth>4</fourth>
</Children>
</Parent>';
$xml = new SimpleXMLElement($string);
$children = $xml->xpath('/Parent/Children/*');
$result = array();
foreach ($children as $child){
$result[] = $child->getName();
}
print_r($result);