使用DOMDocument解析html(parsing html with DOMDocument)

 我在php中使用DOMDocument解析html。 
 
 我发现我无法使用xpath查询选择所有内容。 但是getElementsByTagName（）方法工作正常。 
 
 这是代码： 
 
$xml = new DOMDocument();
$xml->load("file.html");
$xpath = new DOMXPath($xml);

$links = $xpath->query("//a");
$links2 = $xml->getElementsByTagName("a");

foreach($links as $link){
    echo "<br>$k: ".$link->nodeValue; // this doesn't print the node value. $links is empty
}
foreach($links2 as $link){
    echo "<br>$k: ".$link->nodeValue; // this prints OK the node value
}
 
 我原以为xpath-> query（“// a”）与getElementsByTagname（“a”）相同，但显然不是。 
 
 谁能告诉我为什么他们不一样了。 或者，如果它们是，我使用xpath查询选择节点我做错了什么？ 
 
 谢谢 

I'm parsing html with DOMDocument in php.
 
I found I'm unable to select all using an xpath query. However the getElementsByTagName() method works fine.
 
Here is the code:
 
$xml = new DOMDocument();
$xml->load("file.html");
$xpath = new DOMXPath($xml);

$links = $xpath->query("//a");
$links2 = $xml->getElementsByTagName("a");

foreach($links as $link){
    echo "<br>$k: ".$link->nodeValue; // this doesn't print the node value. $links is empty
}
foreach($links2 as $link){
    echo "<br>$k: ".$link->nodeValue; // this prints OK the node value
}
 
I'd have thought xpath->query("//a") would be the same as getElementsByTagname("a") but apparently isn't.
 
Could anybody tell me why they aren't the same. Or if they are, what am I doing wrong to select the nodes using the xpath query?
 
Thank you

原文：https://stackoverflow.com/questions/6730555