PHP: documentElement->childNodes warning

问题

$xml = file_get_contents(example.com);

$dom = new DomDocument();
$dom->loadXML($xml);

$items = $dom->documentElement;

foreach($items->childNodes as $item) { 
 $childs = $item->childNodes;
 foreach($childs as $i) {
  echo $i->nodeValue . "<br />";
 }
}

Now I get this warning in every 2nd foreach:

Warning: Invalid argument supplied for foreach() in file_example.php  on line 14

Please help guys. Thanks!

回答1:

Some nodes don't have children, so you're passing a null (invalid) argument to the foreach (just like the warning says).

To avoid the warnings you need to check if the current node has any children. For that you can use the DOMNode::hasChildNodes() method:

foreach($items->childNodes as $item) { 
    if ($item->hasChildNodes()) {
        $childs = $item->childNodes;
        foreach($childs as $i) {
            echo $i->nodeValue . "<br />";
        }
    }
}

来源：https://stackoverflow.com/questions/2511779/php-documentelement-childnodes-warning