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.Numerics;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

// https://stackoverflow.com/questions/49308293/parse-0x0-as-biginteger-by-json-net

​

    public class BigIntegerConverter : JsonConverter

    {

        public override bool CanConvert(Type objectType) { return objectType == typeof(BigInteger ); }

​

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

        {

            var token = JToken.Load(reader);

            if (token.Type == JTokenType.String && ((string)(JValue)token).StartsWith("0x"))

            {

                // 0 must be prepended to avoid a negative value

                // https://stackoverflow.com/questions/30119174/converting-a-hex-string-to-its-biginteger-equivalent-negates-the-value

                var s = "0" + ((string)(JValue)token).Substring(2);

                //Console.WriteLine(s);

                return BigInteger.Parse(s, NumberStyles.HexNumber);

            }

            return token.ToObject<BigInteger>();

        }

​

        public override bool CanWrite { get { return false; } }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

        {

            throw new NotImplementedException();

        }

    }

​

    public class XResult 

    { 

        [JsonConverter(typeof(BigIntegerConverter))]

        public BigInteger result { get; set; } 

    }

​

    class TestClass

    {

        public static void Test()

        {

            foreach (var json in GetJson())

            {

                Test(json);

            }

        }

        public static void Test(string json)

        {

            Console.WriteLine("Deserializing directly: ");

            var result1 = JsonConvert.DeserializeObject<XResult>(json);

            Console.WriteLine(JsonConvert.SerializeObject(result1));

            Console.WriteLine("\nDeserializing indirectly via JToken: ");

            var result2 = JToken.Parse(json).ToObject<XResult>();

            Console.WriteLine(JsonConvert.SerializeObject(result2));            

        }

        static IEnumerable<string> GetJson()

        {

            var json = new []

            {

                @"{""result"":""0x0""}",

                @"{""result"":""0xF""}",

                @"{""result"":""0x00FFFFFFFFFFFFFFFFFFFFFFFFFFFFF000000000000000000FFFFFFFFFFFFFFF""}",

            };

            return json;

        }

    }

​

    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;

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            IsTrue(value, "failed");

        }

​

        public static void IsTrue(bool value, string message)

        {

            if (value == false)

                throw new AssertionFailedException(message ?? "failed");

        }

    }

​