With PHP preg_match_all, get value of href

问题

I don'T really understabd how regular expressions works even after I read this tutorial http://www.webcheatsheet.com/php/regular_expressions.php

Here is what I need to find:

<link type="text/html" rel="alternate" href="http://link"/>

And it should return:

http://link

Here is what I tried:

$find = preg_match_all(
    '/<link type="text/html" rel="alternate" href=".*',
    $file,
    $patterns2
);

You can laught :)

Thanks in advance for your help and your time :)

回答1:

using simplexml

$html = '<link type="text/html" rel="alternate" href="http://link"/>';
$xml  = simplexml_load_string($html);
$attr = $xml->attributes();

using dom

$dom = new DOMDocument;
$dom->loadHTML($html);
$nodes = $dom->getElementsByTagName('link');
$attr  = $nodes->item(0)->getAttribute('href');

回答2:

Parsing (X)HTML with regex is almost certainly wrong. Use a dedicated XML parser. There are plenty available for php.

回答3:

You have to cover the needed text-chunk in brackets like (.*), that is what will be returned

This one is working for me

<?php
preg_match_all('/<link type="text\/html" rel="alternate" href="(.*)"\/>/','<link type="text/html" rel="alternate" href="http://link"/>',$patterns2);
print_r($patterns2);
?>

来源：https://stackoverflow.com/questions/4587304/with-php-preg-match-all-get-value-of-href