Specify HTML elements from *.html file and insert value to there [closed]

Question

I have a task like this, I need to create a winform with flow like this:

a textbox for user input a string value. Then, I choose an available file html, and I want to specify <H1> tag and insert these string to it, for example.

I found something on the internet like HtmlTextWriter class but it does not seem feasible...

Maybe I have not understood yet about HtmlTextWriter . Could you tell me how to use this...Special Thanks for your help.

Answer 1

Use XElement to rebuild the HTML document

    string html = @"<html>
        <body><div></div></body>
    </html>";

    string userIput = "hello world";

    var document = XElement.Parse(html);
    var newDoc = new XElement(document.Name,
        new XElement("body",
            new XElement("div",
                new XElement("h1") { Value = userIput })));