[Solved] how to remove all tag in c# using regex.replace [closed]

Question

You should never use regex to parse html, you need html parser. Here is an example how you can do it.

You need to add this reference in your project:

Install-Package HtmlAgilityPack

The code:

 static void Main(string[] args)
        {
            string html = @"<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

<table>
    <tr>
        <td>A!!</td>
        <td>te2</td>
        <td>2!!</td>
        <td>te43</td>
        <td></td>
        <td> !!</td>
        <td>.!!</td>
        <td>te53</td>
        <td>te2</td>
        <td>texx</td>
    </tr>
</table>

<h4 class=""nikstyle_title""><a rel=""nofollow"" target=""_blank"" href=""http://www.niksalehi.com/ccount/click.php?ref=ZDNkM0xuQmxjbk5wWVc1MkxtTnZiUT09&id=117""><span class=""text-matn-title-bold-black"">my text</span></a></h4>

</body>
</html>";

            HtmlDocument doc = new HtmlDocument();
            doc.LoadHtml(html);

            List<HtmlNode> tdNodes = doc.DocumentNode.Descendants().Where(x => x.Name == "h4" && x.Attributes.Contains("class") && x.Attributes["class"].Value.Contains("nikstyle_title")).ToList();


            foreach (HtmlNode node in tdNodes)
            {
                node.InnerHtml = "";
            }

            string html2 = doc.DocumentNode.InnerHtml;
        }

EDIT:

For your second desire -> Remove every <a></a> tag with `href=”http://www.sample.com”:

    static void Main(string[] args)
        {
            string html = @"<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

<table>
    <tr>
        <td>A!!</td>
        <td>te2</td>
        <td>2!!</td>
        <td>te43</td>
        <td></td>
        <td> !!</td>
        <td>.!!</td>
        <td>te53</td>
        <td>te2</td>
        <td>texx</td>

    </tr>
</table>

<h4 class=""nikstyle_title""><a rel=""nofollow"" target=""_blank"" href=""http://www.sample.com""><span class=""text-matn-title-bold-black"">my text</span></a></h4>
<div><a rel=""nofollow"" target=""_blank"" href=""http://www.sample.com""><span class=""text-matn-title-bold-black"">my text</span></a></div>
</body>
</html>";

            HtmlDocument doc = new HtmlDocument();
            doc.LoadHtml(html);

            List<HtmlNode> tdNodes = doc.DocumentNode.Descendants().Where(x => x.Name == "a" && x.Attributes.Contains("href") && x.Attributes["href"].Value.Contains("http://www.sample.com")).ToList();

            foreach (HtmlNode node in tdNodes)
            {

                node.Remove();
            }

            string html2 = doc.DocumentNode.InnerHtml;
        }

Also personally I prefer to use @ for escaping because it is more readable, you can try like in my example. When you are using @ you will escape with double quotes-example: class=""a"";

Accepted Answer