正则表达式。 在特定标签之间查找标签

Question

There are an html code that contains many hrefs. But I don't need all of hrefs. I want to get only hrefs contained in the div:

<div class="category-map second-links"> 
*****
</div> <p class="sec">

what i want to see as a result:

<a href='xxx'>yyy</a>
<a href='zzz'>www</a>
...

My version (not working):

(?<=<div class=\"category-map second-links\">)(.+?(<a href=\".+?".+?>.+<\/a>))+(?=<\/div> <p class="sec">)

Answer 1

If you load your HTML into a DOM document, you can use Xpath to query nodes from it.

All a elements inside the document:

• //a

That have an ancestor/a parent div element:

• //a[ancestor:div]

With the class attribute category-map second-links

• //a[ancestor::div[@class = "category-map second-links"]]

Get the href attributes of the filtered a elements (Optionally)

• //a[ancestor::div[@class = "category-map second-links"]]/@href

Full Example:

$html = <<<'HTML'
<div class="category-map second-links"> 
*****
    <!--<div class="category-map second-links"> Comment hacks --> 
    <div class="category-map second-links">
        <a href='xxx'>yyy</a>
        <a href='zzz'>www</a>
...
    </div>
<div class="category-map second-links"> 
*****
    <!--<div class="category-map second-links"> Comment hacks --> 
    <div class="category-map second-links">
        <a href='aaa'>bbb</a>
        <a href='ccc'>ddd</a>
...
    </div>
</div> <p class="sec">
HTML;

$dom = new DOMDocument();
$dom->loadHtml($html);
$xpath = new DOMXpath($dom);

// fetch the href attributes
$hrefs = array();
foreach ($xpath->evaluate('//a[ancestor::div[@class = "category-map second-links"]]/@href') as $node) {
  $hrefs[] = $node->value;
}
var_dump($hrefs);

// fetch the a elements an read some data from them
$linkData = array();
foreach ($xpath->evaluate('//a[ancestor::div[@class = "category-map second-links"]]') as $node) {
  $linkData[] = array(
    'href' => $node->getAttribute('@href'),
    'text' => $node->nodeValue,
  );
}
var_dump($linkData);

// fetch the a elements and store their html
$links = array();
foreach ($xpath->evaluate('//a[ancestor::div[@class = "category-map second-links"]]') as $node) {
  $links[] = $dom->saveHtml($node);
}
var_dump($links);