using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/55983525/json-net-deserializeanonymoustype-returns-biginteger-instead-of-uint64

​

    class TestClass

    {

        public static void Test()

        {

            Type t = typeof(UInt64);

            var def = Activator.CreateInstance(t);

            Console.WriteLine(def.GetType());

​

            string json = "18446744073709551615";

            object parsedObject1 = JsonConvert.DeserializeAnonymousType(json, def);

            Console.WriteLine(parsedObject1.GetType());         

            object parsedObject = JsonConvert.DeserializeObject(json, def.GetType());

            Console.WriteLine(parsedObject.GetType());          

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​