Using mshtml doesn't work

Question

I have a c# app and i have tried using some mshtml elements. But i have a problem. The using mshtml; namespace gives me a error is Visual Studio 2012.

Here is my source code,

namespace Tagger
{

    using mshtml;
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Runtime.CompilerServices;
    using System.Text;

    public class HTMLForm
    {
        private string _action = "";
        private string _method = "";
        public Hashtable Inputs = new Hashtable();

        public HTMLForm(IHTMLFormElement element)
        {
            this._method = element.method;
            this._action = element.action;
            foreach (IHTMLInputElement element2 in (IHTMLElementCollection) element.tags("input"))
            {
                try
                {
                    string name = element2.name;
                    string str2 = element2.value;
                    if (name == null)
                    {
                        name = element2.type;
                    }
                    this.Inputs.Add(name, str2);
                }
                catch
                {
                }
            }
        }

        public static HTMLForm[] GetAllForms(string html)
        {
            List<HTMLForm> list = new List<HTMLForm>();
            HTMLDocument document = (HTMLDocument) Activator.CreateInstance(Type.GetTypeFromCLSID(new Guid("25336920-03F9-11CF-8FD0-00AA00686F13")));
            document.write(new object[] { html });
            document.close();
            foreach (IHTMLFormElement element in document.forms)
            {
                list.Add(new HTMLForm(element));
            }
            return list.ToArray();
        }

        public static HTMLForm GetFormByAction(string html, string action)
        {
            foreach (HTMLForm form in GetAllForms(html))
            {
                if (form.Action.ToLower() == action.ToLower())
                {
                    return form;
                }
            }
            return null;
        }

        public string ToPostData()
        {
            StringBuilder builder = new StringBuilder();
            foreach (string str in this.Inputs.Keys)
            {
                object obj2 = this.Inputs[str];
                string str2 = (obj2 == null) ? "" : obj2.ToString();
                builder.AppendFormat("{0}={1}&", HTTPBase.encode(str), HTTPBase.encode(str2));
            }
            if (builder.Length > 1)
            {
                return builder.ToString().Substring(0, builder.Length - 1);
            }
            return "";
        }

        public string Action
        {
            get
            {
                return this._action;
            }
            set
            {
                this._action = value;
            }
        }

        public string Method
        {
            get
            {
                return this._method;
            }
            set
            {
                this._method = value;
            }
        }        
    }
}

But i can't use the functions of htmlelement, IHTMLElementCollection . The compiler gives me a error.

Error 1 The type or namespace name 'mshtml' could not be found (are you missing a using directive or an assembly reference?)

Error 5   The type or namespace name 'HTMLDocument' could not be found (are 

you missing a using directive or an assembly reference?

Error 2 The type or namespace name 'IHTMLFormElement' could not be found (are you missing a using directive or an assembly reference?)

Error 3 The type or namespace name 'IHTMLElementCollection' could not be found (are you missing a using directive or an assembly reference?)

Error 4 The type or namespace name 'HTMLDocument' could not be found (are you missing a using directive or an assembly reference?)

Answer 1

Right click on References in your project in Solution Explorer. Then click Add Reference.... In Assemblies type in search 'HTML' and you'll see Microsoft.mshtml. Add this to your project and you could use HTMLDocument. Good luck