using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

public class Program

{

    public class Person

    {

        public int Id {get; set;}

        //[JsonProperty("first_name")]

        public string FirstName {get; set;}

        //[JsonProperty("last_name")]

        public string LastName {get; set;}

    }

    private static void PrintDeserializedObject(string obj, DefaultContractResolver resolver) 

    {

        var person = JsonConvert.DeserializeObject<Person>(obj, new JsonSerializerSettings

        {

            ContractResolver = resolver,

        });

        Console.WriteLine("{0}.{1}.{2}", person.Id, person.FirstName, person.LastName);

    }

    public static void Main()

    {

        var firstObj = @"{

            ""id"" : 1,

            ""first_name"": ""Jon"",

            ""last_name"": ""Doe""

            }";

        var secondObj = @"{

            ""id"" : 1,

            ""firstName"": ""Jon"",

            ""lastName"": ""Doe""

            }"; 

        DefaultContractResolver snakeResolver = new DefaultContractResolver

        {

            NamingStrategy = new SnakeCaseNamingStrategy()

        };

​

        PrintDeserializedObject(firstObj, snakeResolver);

        PrintDeserializedObject(secondObj, new CamelCasePropertyNamesContractResolver());

    }

}