How can I find the contents of the first h3 tag?_问答_开发者

How can I find the contents of the first h3 tag?

开发者 https://www.devze.com 2023-01-19 02:52 出处：网络

I am looking for a r开发者_开发百科egex to find the contents of the first <h3> tag. What can I use there?You should use php\'s DOM parser instead of regular expressions. You\'re looking for some

I am looking for a r开发者_开发百科egex to find the contents of the first <h3> tag. What can I use there?

You should use php's DOM parser instead of regular expressions. You're looking for something like this (untested code warning):

$domd = new DOMDocument();
libxml_use_internal_errors(true);
$domd->loadHTML($html_content);
libxml_use_internal_errors(false);

$domx = new DOMXPath($domd);
$items = $domx->query("//h3[position() = 1]");

echo $items->item(0)->textContent;

Well, a simple solution would be the following:

preg_match( '#<h3[^>]*>(.*?)</h3>#i', $text, $match );
echo $match[1];

For everything more complex, you should consider using a HTML document parser though.

The DOM approach:

<?php

$html = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head><title></title>
</head>
<body>

<h1>Lorem ipsum<h1>
<h2>Dolor sit amet<h2>
<h3>Duis quis velit est<h3>
<p>Cras non tempor est.</p>
<p>Maecenas nec libero leo.</p>
<h3>Nulla eu ligula est</h3>
<p>Suspendisse potenti.</p>

</body>
</html>
';

$doc = new DOMDocument;
$doc->loadHTML($html);

$titles = $doc->getElementsByTagName('h3');
if( !is_null($titles->item(0)) ){
    echo $titles->item(0)->nodeValue;
}

?>

Here's an explanation why parsing HTML with regular expressions is evil. Anyway, this is a way to do it...

$doc = new DOMDocument();
$doc->loadHTML($text);
$headings = $doc->getElementsByTagName('h3');
$heading = $headings->item(0);
$heading_value = (isset($heading->nodeValue)) ? $heading->nodeValue : 'Header not found';

First of all: regular expressions aren't a proper tool for parsing HTML code. However in this case, they should be good enough, cause H3 tags cannot be nested.

preg_match_all('/<h3[^>]*>(.*?)<\/h3>/si', $source, $matches);

$matches variable should contains content from H3 tagas.

Use an xpath expression like

"/html/body/h3[0]"

this will select the whole first h3 node.

Note that this will not work on ill-formed html.

PHP has the ability to parse HTML DOMs natively - you almost certainly want to use that instead of regex.

See this page for details: http://php.net/manual/en/book.dom.php

And check the related questions down the right hand side for people asking very similar questions.

preg_match("/&lt;h3&gt;(.*)&lt;\/h3&gt;/", $search_in_this_string, $put_matches_in_this_var);

How can I find the contents of the first h3 tag?

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