How can I Convert HTML to Text in C#?

Question

I'm looking for C# code to convert an HTML document to plain text.

I'm not looking for simple tag stripping , but something that will output plain text with a reasonable preservation of the original layout.

The output should look like this:

Html2Txt at W3C

I've looked at the HTML Agility Pack, but I don't think that's what I need. Does anyone have any other suggestions?

EDIT: I just download the HTML Agility Pack from CodePlex, and ran the Html2Txt project. What a disappointment (at least the module that does html to text conversion)! All it did was strip the tags, flatten the tables, etc. The output didn't look anything like the Html2Txt @ W3C produced. Too bad that source doesn't seem to be available. I was looking to see if there is a more "canned" solution available.

EDIT 2: Thank you everybody for your suggestions. FlySwat tipped me in the direction i wanted to go. I can use the System.Diagnostics.Process class to run lynx.exe with the "-dump" switch to send the text to standard output, and capture the stdout with ProcessStartInfo.UseShellExecute = false and ProcessStartInfo.RedirectStandardOutput = true. I'll wrap all this in a C# class. This code will be called only occassionly, so i'm not too concerned about spawning a new process vs. doing it in code. Plus, Lynx is FAST!!

Answer 1

What you are looking for is a textmode DOM renderer that outputs text, much like Lynx or other Text browsers...This is much harder to do that you would expect.

Answer 2

The easiest would probably be tag stripping combined with replacement of some tags with text layout elements like dashes for list elements (li) and line breaks for br's and p's. It shouldn't be too hard to extend this to tables.

Answer 3

Have you tried http://www.aaronsw.com/2002/html2text/ it's Python, but open source.

Answer 4

I don't know C#, but there is a fairly small & easy to read python html2txt script here: http://www.aaronsw.com/2002/html2text/

Answer 5

I've heard from a reliable source that, if you're doing HTML parsing in .Net, you should look at the HTML agility pack again..

http://www.codeplex.com/htmlagilitypack

Some sample on SO..

http://stackoverflow.com/questions/655603/html-agility-pack-parsing-tables

Answer 6

Another post suggests the HTML agility pack:

This is an agile HTML parser that builds a read/write DOM and supports plain XPATH or XSLT (you actually don't HAVE to understand XPATH nor XSLT to use it, don't worry...). It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML. The object model is very similar to what proposes System.Xml, but for HTML documents (or streams).

Answer 7

Not a C# solution, but you might want to take a look at this. A HTML to Markdown converter written in PHP. This, of course, doesn't convert all tags.

Answer 8

You could use this:

 public static string StripHTML(string HTMLText)
        {
            Regex reg = new Regex("<[^>]+>", RegexOptions.IgnoreCase);
            return reg.Replace(HTMLText, "");
        }

Answer 9

I have used Detagger in the past. It does a pretty good job of formatting the HTML as text and is more than just a tag remover.

Answer 10

This is another solution to convert HTML to Text or RTF in C#:

    SautinSoft.HtmlToRtf h = new SautinSoft.HtmlToRtf();
    h.OutputFormat = HtmlToRtf.eOutputFormat.TextUnicode;
    string text = h.ConvertString(htmlString);

This library is not free, this is commercial product.

Answer 11

I have recently blogged on a solution that worked for me by using a Markdown XSLT file to transform the HTML Source. The HTML source will of course need to be valid XML first

Answer 12

Nice idea with the Lynx! Have you tested out that solution with a high user volume (load test)?

If you already have a C# HTML editor, like CuteEditor, it may have C# classes you can use to do the conversion you are trying to accomplish.

Answer 13

I think the easiest way is to make a 'string' extension method (based on what user Richard have suggested):

using System;
using System.Text.RegularExpressions;

public static class StringHelpers
{
    public static string StripHTML(this string HTMLText)
        {
            var reg = new Regex("<[^>]+>", RegexOptions.IgnoreCase);
            return reg.Replace(HTMLText, "");
        }
}

Then just use this extension method on any 'string' variable in your program:

var yourHtmlString = "<div class=\"someclass\"><h2>yourHtmlText</h2></span>";
var yourTextString = yourHtmlString.StripHTML();

I use this extension method to convert html formated comments to plain text so it will be displayed correctly on a crystal report, and it works perfect!

Answer 14

You can use WebBrowser control to render in memory your html content. After LoadCompleted event fired...

IHTMLDocument2 htmlDoc = (IHTMLDocument2)webBrowser.Document;
string innerHTML = htmlDoc.body.innerHTML;
string innerText = htmlDoc.body.innerText;