regular expression not matching, what am I doing wrong?

Question

I'm trying to make a replacement between a string containing a link, with the same string encapsulated in html href blocks. I'm new to regular expressions and have been reading up on them - I've come up with this expression going through SO and other sites.

$s = 'This is a stupid site: www.etsy.com';
$regEx = '#(^www\.|^http://)([a-zA-Z0-9/?\-&=_\.]+\.com|\.net|\.org|\.ca)|(/[a-zA-Z0-9/?\-_&=\.]+)#';
$ret = preg_replace( $regEx, "<a href='$1$2$3'>$1$2$3</a>", $s);
echo $ret;

This doesn't return me a link at all

and this doesn't include "http://" in the link:

$s = 'This is a stupid video http://www.youtube.com/watch?v=MkXVM6ad9nI';
$regEx = '#(^www\.|^http://)([a-zA-Z0-9/?\-&=_\.]+\.com|\.net|\.org|\.ca)|(/[a-zA-Z0-9/?\-_&=\.]+)#';
$ret = preg_replace( $regEx, "<a href='$1$2$3'>$1$2$3</a>", $s);
echo $ret;

I'm still trying so this might change... but any help would be appreciated as I'm nearing my wits end.

Thank you in advance for your time

P.S: I tried this in RegexBuddy and the whole string gets highlighted when I test... so I'm really wondering what I'm doing wrong.

`^` anchors the start of a line or the whole string subject. — mario, Nov 09 '14 at 18:36
What you are doing wrong is that you are trying to parse HTML with regular expressions, which is impossible, since HTML is not a regular language. Use a HTML parser instead. — The Paramagnetic Croissant, Nov 09 '14 at 18:37
possible duplicate of [RegEx match open tags except XHTML self-contained tags](http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags) — The Paramagnetic Croissant, Nov 09 '14 at 18:40
I haven't dug deep enough to find the answer, but the `#` is an X-mode comment. — Bob Brown, Nov 09 '14 at 18:42
@TheParamagneticCroissant: He's parsing a URL to build HTML. That ought to work. — Bob Brown, Nov 09 '14 at 18:45
Give up on the regular expression. Break this into two parts: Find a URL within a string, then use PHP's `parse_url` function to parse the URL. — Bob Brown, Nov 09 '14 at 18:46
@mario - thank you, that actually fixed it. I do get my links now with this regular expression changed to not have the ^. — wribit, Nov 09 '14 at 18:51
@Bob Brown, thank you as well - I'll be implementing a different solution using parse_url — wribit, Nov 09 '14 at 18:53

Croises · Answer 1 · 2014-11-09T19:46:57.300

0

Try with:

$s = 'This is a stupid site: www.etsy.com';
$regEx = '#(www\.|http://)([a-zA-Z0-9\/?\-&=_\.]+\.com|\.net|\.org|\.ca)(/[a-zA-Z0-9/?\-_&=\.]*)?#';
$ret = preg_replace( $regEx, "<a href='$1$2$3'>$1$2$3</a>", $s);
echo $ret;

And test HERE

edited Nov 09 '14 at 19:46

answered Nov 09 '14 at 19:29

Croises

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score 0 · Answer 2 · answered Nov 10 '14 at 09:53

Your regex matches, for example:

www.whatever.com

or

www.net

but not

www.whatever.net

You have to group the TLDs:

$regEx = '#(^www\.|^http://)([a-zA-Z0-9/?\-&=_\.]+(\.com|\.net|\.org|\.ca))|(/[a-zA-Z0-9/?\-_&=\.]+)#';
//                                         here __^   and         here  __^

You could also simplify it:

$regEx = '#^((?:www\.|http://)[\w/.-]+\.(?:com|net|org|ca))#';
$ret = preg_replace( $regEx, "<a href='$1'>$1</a>", $s);

Where:

(?:...) is a non capture group.
\w stands for [a-zA-Z0-9_]

regular expression not matching, what am I doing wrong?

2 Answers2