using System;

using System.Linq.Expressions;

using System.Collections.Generic;

using System.Text;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Expression<Func<Foo, C>> expr = x => ((B)(x.A.B)).C;

        var result = new List<string>();

        Construct(expr.Body, result);

        Console.WriteLine(string.Join(".", result.AsEnumerable().Reverse()));       

    }

    private static void Construct(Expression expr, List<string> result)

    {

        switch (expr)

        {

            case MemberExpression member:

                result.Add(member.Member.Name);

                Construct(member.Expression, result);

                break;

            case UnaryExpression unary:

                Construct(unary.Operand, result);

                break;

        }

    }

}

​

public class Foo

{

    public A A { get; set; }    

}

public class A 

{

    public object B { get; set; }   

}

public class B

{

    public C C { get; set; }    

}

public class C

{

}