using System;

using System.IO;

using System.Reflection;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

public class Program

{

    public static object DeepCopy(object obj)

    {

        if (obj == null)

            return null;

        Type type = obj.GetType();

​

        if (type.IsValueType || type == typeof(string))

        {

            return obj;

        }

        else if (type.IsArray)

        {

            Type elementType = type.GetElementType();

            var array = obj as Array;

            Array copied = Array.CreateInstance(elementType, array.Length);

            for (int i = 0; i < array.Length; i++)

            {

                copied.SetValue(DeepCopy(array.GetValue(i)), i);

            }

            return Convert.ChangeType(copied, obj.GetType());

        }

        else if (type.IsClass)

        {

​

            object toret = Activator.CreateInstance(obj.GetType());

            FieldInfo[] fields = type.GetFields(BindingFlags.Public |

                        BindingFlags.NonPublic | BindingFlags.Instance);

            foreach (FieldInfo field in fields)

            {

                object fieldValue = field.GetValue(obj);

                if (fieldValue == null)

                    continue;

                field.SetValue(toret, DeepCopy(fieldValue));

            }

            return toret;

        }

        else

            throw new ArgumentException("Unknown type");

    }

    public class Base

    {

    }

    [System.Serializable]

    public class A : Base

    {

        public string str = "A";

        public virtual void Print()

        {

            Console.WriteLine("A " + str);

        }

        public A GetNewInstance()

        {

            return DeepCopy(this) as A;

        }

    }

    [System.Serializable]

    public class B : A

    {

        public B() { str = "B"; }

        public override void Print()

        {

            Console.WriteLine("B " + str);

        }

    }

​

    public static void Main()

    {

        A obj = new B();

        var clone = obj.GetNewInstance();

        clone.Print();

    }

}