A pattern to parse links in a text

Question

I have some texts that may contain links like this:

<a rel="nofollow" target="_blank" href="http://loremipsum.net/">http://loremipsum.net/</a>
Lorem ipsum dolor sit amet, consectetuer adipiscing elit, <a rel="nofollow" target="_blank" href="http://loremipsum.net/">http://loremipsum.net/</a> sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.

I want to find links (a tags) inside this text, what is the regex pattern for that?

This pattern doesn't work:

const string UrlPattern = @"(http|ftp|https):\/\/[\w\-_]+(\.[\w\-_]+)+([\w\-\.,@?^=%&amp;:/~\+#]*[\w\-\@?^=%&amp;/~\+#])?";
var urlMatches = Regex.Matches(text, UrlPattern);

thanks

A regex that would parse any and all `` tags would be a huge unmaintainable monstrosity of a black box. Is that the one you want? — Jon, Mar 12 '14 at 13:37
Would you consider using another solution than a regex, for example the HtmlAgilityPack ? If so you may avoid many pains at a later time — samy, Mar 12 '14 at 13:38
@HenkHolterman It's exactly the same as example above in question. — user3293835, Mar 12 '14 at 13:45
[Obligatory link](http://stackoverflow.com/q/4231382/471272): please link to answer, not to non-answers. — tchrist, Jun 08 '14 at 20:08

Sergey Berezovskiy · Accepted Answer · 2014-03-12T18:30:04.110

1

I suggest to use HtmlAgilityPack for parsing HTML (its available from NuGet):

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(html);
var links = doc.DocumentNode.SelectNodes("//a[@href]")
               .Select(a => a.Attributes["href"].Value);

Result:

[
  "http://loremipsum.net/",
  "http://loremipsum.net/"
]

Suggested reading: Parsing Html The Cthulhu Way

edited Mar 12 '14 at 18:30

answered Mar 12 '14 at 13:38

Sergey Berezovskiy

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My name is samy, and i approve this answer – samy Mar 12 '14 at 13:39
@samy my name is Sergey, and I say thanks to you :) – Sergey Berezovskiy Mar 12 '14 at 13:49

Vasiliy vvscode Vanchuk · Answer 2 · 2014-03-12T14:25:28.577

0

maybe so

Regex regexObj = new Regex(@"<a.+?href=(['|""])(.+?)\1");
resultString = regexObj.Match(subjectString).Groups[2].Value;

for list of matches

StringCollection resultList = new StringCollection();

Regex regexObj = new Regex(@"<a.+?href=(['|""])(.+?)\1");
Match matchResult = regexObj.Match(subjectString);
while (matchResult.Success) {
    resultList.Add(matchResult.Groups[2].Value);
    matchResult = matchResult.NextMatch();
}

edited Mar 12 '14 at 14:25

answered Mar 12 '14 at 13:40

Vasiliy vvscode Vanchuk

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Can you add more description? – Keith Pinson Mar 12 '14 at 14:02
1

change code - use regexp ( select url from href attribute of a tag) – Vasiliy vvscode Vanchuk Mar 12 '14 at 14:26

score 0 · Answer 3 · answered Mar 12 '14 at 13:40

You should use an XML parser which is much more robust and reliable in this kind of task. But if you want something very quick and very dirty, here it is:

<a.*?<\/a>

If this is too simple, and you need to capture the link address or the link content, go with this:

<a.*?href="(?<address>.*?)".*?>(?<content>.*?)<\/a>

They both don't match correctly nested tags.

A pattern to parse links in a text

3 Answers3