using System;

using System.Collections.Generic;

using System.Linq;

using System.Web; //Remember to add this one to References...

​

namespace ConsoleApplication1

{

    public class Program

    {

        public static void Main(string[] args)

        {

            //Dummy up a Dictionary (boilerplate)    

            Dictionary<String, String> formVars = new Dictionary<string, string>();

            formVars["hey"] = "you guys";

            formVars["one"] = "eyed Willie";

            formVars["anyone remember"] = "Goonies?";

​

#region important part here

​

            //Make the magic happen (this is the part you want):

            string g = String.Join("&", formVars.Select(x => HttpUtility.UrlEncode(x.Key) + "=" + HttpUtility.UrlEncode(x.Value)));

            byte[] toPost = System.Text.Encoding.UTF8.GetBytes(g);

#endregion

​

            //Show it worked:

            Console.WriteLine("Dict key/value pairs: \n" + String.Join("\n", formVars.Select(x => "  " + x.Key + ": " + x.Value)));

            Console.WriteLine("");

            Console.WriteLine("The full post string is:\n" + g);

        }

    }

}