using System;

public class Program

{

    public static void Main()

    {

        Class1 c = new Class1();

    }

}

​

public class Class1

{

    public Struct1 struct1 {get; private set;}

    public Class1()

    {

        Console.WriteLine(struct1.x);

        struct1.modifySelf();

        Console.WriteLine(struct1.x);

    }

}

​

public struct Struct1

{

    public int x;

    public Struct1(int x)

    {

        this.x = x;

    }

    public void modifySelf()

    {

        this.x = 3;

        Console.WriteLine(this.x);

    }

}