Having a bit of regex headaches with varied links and href delimiters (" and ')

So, I want to match the following link structures with a preg_match_all in php..

<a garbage href="http:/开发者_开发知识库/this.is.a.link.com/?query=this has invalid spaces" possible garbage>
<a garbage href='http://this.is.a.link.com/?query=this also has has invalid spaces' possible garbage>
<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters possible garbage>
<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters>

I can get " and ' deilmited urls one by doing

'#<a[^>]*?href=("|\')(.*?)("|\')#is'

or I can get all 3, but not if there are spaces in the first two with:

'#<a[^>]*?href=("|\')?(.*?)[\s\"\'>]#is'

How can I formulate this so that it will pick up " and ' delimited with potential spaces, but also properly encoded URLs without delimiters.

---

OK, this seems to work:

'#<a[^>]*?href=((["\'][^\'"]+["\'])|([^"\'\s>]+))#is'

($matches[1] contains the urls)

Only annoyance is that quoted urls have the quotes still on, so you'll have to strip them off:

$first = substr($match, 0, 1);
if($first == '"' || $first == "'")
    $match = substr($match, 1, -1);

---

EDIT: I have edited this to work a little better than I originally posted.

You almost have it in the second regex:

'#<a[^>]*?href=("|\')?(.*?)[\\1|>]#is'

Returns the following array:

array(3) {
  [0]=>
  array(4) {
    [0]=>
    string(92) "<a garbage href="http://this.is.a.link.com/?query=this has invalid spaces" possible garbage>"
    [1]=>
    string(101) "<a garbage href='http://this.is.a.link.com/?query=this also has has invalid spaces' possible garbage>"
    [2]=>
    string(94) "<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters possible garbage>"
    [3]=>
    string(77) "<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters>"
  }
  [1]=>
  array(4) {
    [0]=>
    string(1) """
    [1]=>
    string(1) "'"
    [2]=>
    string(0) ""
    [3]=>
    string(0) ""
  }
  [2]=>
  array(4) {
    [0]=>
    string(74) "http://this.is.a.link.com/?query=this has invalid spaces" possible garbage"
    [1]=>
    string(83) "http://this.is.a.link.com/?query=this also has has invalid spaces' possible garbage"
    [2]=>
    string(77) "http://this.is.a.link.com/?query=no_spaces_but_no_delimiters possible garbage"
    [3]=>
    string(60) "http://this.is.a.link.com/?query=no_spaces_but_no_delimiters"
  }
}

Works with or without delimiters.

---

Use a DOM parser. You cannot parse (x)HTML with regular expressions.

$html = <<<END
<a garbage href="http://this.is.a.link.com/?query=this has invalid spaces" possible garbage>
<a garbage href='http://this.is.a.link.com/?query=this also has has invalid spaces' possible garbage>
<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters possible garbage>
<a garbage href=http://this.is.a.link.com/?query=no_spaces_but_no_delimiters>
END;

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

$items = $domd->getElementsByTagName("a");
foreach ($items as $item) {
  var_dump($item->getAttribute("href"));
}

---

When you say you want to match them, are you trying to extract information out of the links, or simply find hyperlinks with a href? If you're after only the latter, this should work just fine:

/<a[^>]*href=[^\s].*?>/

---

As @JasonWoof indicated, you need to use an embedded alternation: one alternative for quoted URLs, one for non-quoted. I also recommend using a capturing group to determine which kind of quote is being used, as @DanHorrigan did. With the addition of a negative lookahead ((?!\\2)) and possessive quantifiers (*+), you can create a highly robust regex that is also very quick:

~
<a\\s+[^>]*?\\bhref=
(
  (["'])          # capture the opening quote
  (?:(?!\\2).)*+  # anything else, zero or more times
  \\2             # match the closing quote
|
  [^\\s>]*+   # anything but whitespace or closing brackets
)
~ix

See it in action on ideone. (The doubled backslashes are because the regex is written in the form of a PHP heredoc. I'd prefer to use a nowdoc, but ideone is apparently still running PHP 5.2.)