using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleApp

{

    class Program

    {

        static string hashToPostString(Hashtable ht) {

            string str = "";

            foreach (DictionaryEntry de in ht) {

                str += de.Key + "=" + de.Value + "&";

            }

            return str.Substring(, str.Length - );

        }

        static void Main(string[] args)

        {

            Hashtable ht = new Hashtable();

            ht.Add("username", "");

            ht.Add("password", "202063sb");

            ht.Add("geetest_challenge", "3c2f03027eb7cac324a7cf67f148441d");

            ht.Add("geetest_validate", "21fa24dfd285b955776fd349c5bc5834");

            ht.Add("geetest_seccode", "21fa24dfd285b955776fd349c5bc5834|jordan");            

            string str = hashToPostString(ht);

            Console.Write(str);

            Console.ReadLine();

        }

    }

}

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleApp

{

    class Program

    {

        static string DictionaryToPostString(Dictionary<string, string> ht) {

            string str = "";

            foreach (KeyValuePair<string, string> de in ht) {

                str += de.Key + "=" + de.Value + "&";

            }

            return str.Substring(, str.Length - );

        }

        static void Main(string[] args)

        {

            //定义字典

            Dictionary<string, string> d = new Dictionary<string, string>();

            d.Add("gt", "geetest.gt");

            d.Add("challenge", "geetest.challenge");

            d.Add("model", "");

            d.Add("referer", "http://www.228.com.cn/auth/login");

            d.Add("return", "json");

            d.Add("user", "dragon8jiyan");

            d.Add("pass", "");

            string str = DictionaryToPostString(d);

            Console.Write(str);

            Console.ReadLine();

        }

    }

}