using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var globals_f_settings = new FileSettings { foo = "bing" };

        var globals_d_settings = new DataSettings { bar = "bang" };

        var globals_o_settings = new OtherSettings { baz = "boom" };

        var file_data_class = new File_Save_Data()

        {

            file_Name = "test",

            file_Saved = DateTime.Now,

            f_setting = globals_f_settings,

            d_setting = globals_d_settings,

            o_setting = globals_o_settings

        };

​

        string output_json =

            JsonConvert.SerializeObject(file_data_class, Formatting.Indented);

​

        Console.WriteLine(output_json);

    }

​

}

​

class File_Save_Data 

{

    public string file_Name { get; set; }

    public DateTime file_Saved { get; set; }

    public FileSettings f_setting { get; set; }

    public DataSettings d_setting { get; set; }

    public OtherSettings o_setting { get; set; }

}

​

class FileSettings

{

    public string foo { get; set; } 

}

class DataSettings

{

    public string bar { get; set; } 

}

class OtherSettings

{

    public string baz { get; set; } 

}