Link recognition in c#

Question

In my website, I want to give a feature "to recognize the link". You can see the example in Facebook. Whenever we share a link, it automatically detects it and also find thumbnails. Also If we do the same in Status update, It does the same.

I want to implement the same functionality using asp.net with c#.

Any tutorials, links or demos will be helpful. If you can, please share the logic too.

You should try some codings first, before you ask. Basically it is a `onchange` or `onkeyup` event matching contents with `regex`. — Raptor, Jan 08 '13 at 07:21

erichste · Accepted Answer · 2013-01-08T07:47:52.523

3

This is what i use. On description I use 40 characters, if you want the complete link in description too just remove the substring part...

static string LinksToHTML(string str)
    {
         Regex urlRx = new Regex(@"(?<url>((mailto\:|(news|(ht|f)tp(s?))\://){1}\S+))", RegexOptions.IgnoreCase);

        MatchCollection matches = urlRx.Matches(str);

        foreach (Match match in matches)
        {
            var url = match.Groups["url"].Value;
            str = str.Replace(url, string.Format("<a href=\"{0}\" target=\"blank\">{1}</a>", url, (url.Length > 40 ? url.Substring(0, 40) + "..." : url)));

            //str = str.Replace(url, string.Format("<a href=\"{0}\" target=\"blank\">{1}</a>", url, url));
        }

        return str;
    }

edited Jan 08 '13 at 07:47

answered Jan 08 '13 at 07:32

erichste

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you should handle the link that starts with `https` – Raptor Jan 08 '13 at 07:36
2

Thanks Shivan, you're right, I modified it. – erichste Jan 08 '13 at 07:40
1

I think I liked this one better: http://stackoverflow.com/questions/6173/regular-expression-for-parsing-links-from-a-webpage – erichste Jan 08 '13 at 07:44
Modified mine again according to http://stackoverflow.com/questions/6173/regular-expression-for-parsing-links-from-a-webpage – erichste Jan 08 '13 at 07:48
Yes I agree with this answer, regular expressions are designed for this. – Didac Perez Parera Jan 08 '13 at 07:50

Link recognition in c#

1 Answers1