How to extract Heading tags in PHP from a string?

Question

From a string that contains a lot of HTML, how can I extract all the text from <h1><h2>etc tags into a new variable?

I would like to capture all of the text from these elements and store them in a new variable as comma-delimited values.

Is it possible using preg_match_all()?

Answer 1

First you need to clean up the HTML ($html_str in the example) with tidy:

$tidy_config = array(
    "indent"               => true,
    "output-xml"           => true,
    "output-xhtml"         => false,
    "drop-empty-paras"     => false,
    "hide-comments"        => true,
    "numeric-entities"     => true,
    "doctype"              => "omit",
    "char-encoding"        => "utf8",
    "repeated-attributes"  => "keep-last"
);

$xml_str = tidy_repair_string($html_str, $tidy_config);

Then you can load the XML ($xml_str) into a DOMDocument:

$doc = DOMDocument::loadXML($xml_str);

And finally you can use Horia Dragomir's method:

$list = $doc->getElementsByTagName("h1");
for ($i = 0; $i < $list->length; $i++) {
    print($list->item($i)->nodeValue . "<br/>\n");
}

Or you could also use XPath for more complex queries on the DOMDocument (see http://www.php.net/manual/en/class.domxpath.php)

$xpath = new DOMXPath($doc);
$list = $xpath->evaluate("//h1");