RegEx to get the keywords from HTML

I'm trying to obtain the keywords from an HTML page that I'm scraping with PHP.

So, if the keywords tag looks like this:

<meta name="Keywords" content="MacUpdate, Mac Software, Macintosh Software, Mac Games, Macintosh Games, Apple, Macintosh, Software, iphone, ipod, Games, Demos, Shareware, Freeware, MP3, audio, sound, macster, napster, macintel, universal binary">

I want to get this back:

Ma开发者_Python百科cUpdate, Mac Software, Macintosh Software, Mac Games, Macintosh Games, Apple, Macintosh, Software, iphone, ipod, Games, Demos, Shareware, Freeware, MP3, audio, sound, macster, napster, macintel, universal binary

I've constructed a regex, but it's not doing the trick.

(?i)^(<meta name=\"keywords\" content=\"(.*)\">)

Any ideas?

---

I would use a HTML/XML parser like DOMDocument and XPath to retrieve the nodes from the DOM:

$doc = new DOMDocument();
$doc->loadHTML($html);
$xpath = new DOMXPath($doc);
$keywords = $xpath->query('//meta[translate(normalize-space(@name), "KEYWORDS", "keywords")="keywords"]/@content');
foreach ($keywords as $keyword) {
    echo $keyword->value;
}

The translate function seems to be necessary as PHP’s XPath implementation does not know the lower-case function.

Or you do the filtering with PHP:

$metas = $xpath->query('//meta');
foreach ($metas as $meta) {
    if ($meta->hasAttribute("name") && trim(strtolower($meta->getAttribute("name")))=='keywords' && $meta->hasAttribute("content")) {
        echo $meta->getAttribute("content")->value;
    }
}

---

Use the function get_meta_tags();

Tutorial

---

Stop using regex. It's slow, resource intensive, and not very nimble.

If you're programming in PHP check out http://simplehtmldom.sourceforge.net/ - SimpleDom is powerful enough to get you everything you need in a very simple object-oriented way.

    // Create DOM from URL or file
$html = file_get_html('http://www.google.com/');

// Find all images 
foreach($html->find('img') as $element) 
       echo $element->src . '<br>';

// Find all links 
foreach($html->find('a') as $element) 
       echo $element->href . '<br>';

Another example -

// Example
$html = str_get_html("<div>foo <b>bar</b></div>"); 
$e = $html->find("div", 0);

echo $e->tag; // Returns: " div"
echo $e->outertext; // Returns: " <div>foo <b>bar</b></div>"
echo $e->innertext; // Returns: " foo <b>bar</b>"
echo $e->plaintext; // Returns: " foo bar"

---

(.*) matches everything up to the LAST "(quote) in the document, obviously not what you want. Regex is greedy by default. You need to use

content=\"(.*?)\"

or

content=\"([^\"]*)\"

---

Stop trying to parse HTMl with regular expressions.

RegEx match open tags except XHTML self-contained tags

---

(?i)<meta\\s+name=\"keywords\"\\s+content=\"(.*?)\">

Would produce something like:

preg_match('~<meta\\s+name=\"keywords\"\\s+content=\"(.*?)\">~i', $html, &$matches);

---

This is a simple regex, that matches the first meta keywords tag. It only allows characters, numbers, legal URL characters, HTML entities and spaces to appear inside the content attribute.

$matches = array();
preg_match("/<meta name=\"Keywords\" content=\"([\w\d;,\.: %&#\/\\\\]*)\"/", $html, $matches);
echo $matches[1];