How can I strip HTML tags from a string in ASP.NET?

If it is just stripping all HTML tags from a string, this works reliably with regex as well. Replace:

<[^>]*(>|$)

with the empty string, globally. Don't forget to normalize the string afterwards, replacing:

[\s\r\n]+

with a single space, and trimming the result. Optionally replace any HTML character entities back to the actual characters.

Note:

1. There is a limitation: HTML and XML allow > in attribute values. This solution will return broken markup when encountering such values.
2. The solution is technically safe, as in: The result will never contain anything that could be used to do cross site scripting or to break a page layout. It is just not very clean.
3. As with all things HTML and regex:
   Use a proper parser if you must get it right under all circumstances.

Go download HTMLAgilityPack, now! ;) Download LInk

This allows you to load and parse HTML. Then you can navigate the DOM and extract the inner values of all attributes. Seriously, it will take you about 10 lines of code at the maximum. It is one of the greatest free .net libraries out there.

Here is a sample:

            string htmlContents = new System.IO.StreamReader(resultsStream,Encoding.UTF8,true).ReadToEnd();

            HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
            doc.LoadHtml(htmlContents);
            if (doc == null) return null;

            string output = "";
            foreach (var node in doc.DocumentNode.ChildNodes)
            {
                output += node.InnerText;
            }

Regex.Replace(htmlText, "<.*?>", string.Empty);

I have written a pretty fast method in c# which beats the hell out of the Regex. It is hosted in an article on CodeProject.

Its advantages are, among better performance the ability to replace named and numbered HTML entities (those like & and &203;) and comment blocks replacement and more.

Please read the related article on CodeProject.

Thank you.

string result = Regex.Replace(anytext, @"<(.|\n)*?>", string.Empty);

For those who are complining about Michael Tiptop's solution not working, here is the .Net4+ way of doing it:

public static string StripTags(this string markup)
{
    try
    {
        StringReader sr = new StringReader(markup);
        XPathDocument doc;
        using (XmlReader xr = XmlReader.Create(sr,
                           new XmlReaderSettings()
                           {
                               ConformanceLevel = ConformanceLevel.Fragment
                               // for multiple roots
                           }))
        {
            doc = new XPathDocument(xr);
        }

        return doc.CreateNavigator().Value; // .Value is similar to .InnerText of  
                                           //  XmlDocument or JavaScript's innerText
    }
    catch
    {
        return string.Empty;
    }
}

You can also do this with AngleSharp which is an alternative to HtmlAgilityPack (not that HAP is bad). It is easier to use than HAP to get the text out of a HTML source.

var parser = new HtmlParser();
var htmlDocument = parser.ParseDocument(source);
var text = htmlDocument.Body.Text();

You can take a look at the key features section where they make a case at being "better" than HAP. I think for the most part, it is probably overkill for the current question but still, it is an interesting alternative.