Question

I was working on a demo method and found something strange(at least to me :-))

enter code here  class Program
{
    public void AnotherSwap<T>(T a, T b)  
    {
        T temp;
        temp = a;
        a = b;
        b = temp;

        Console.WriteLine(a);
        Console.WriteLine(b);

    }


    public void swap<T>(T a, T b) where T : MyInt  // Passing without ref
    {
        object temp;
        temp = a.MyProperty;
        a.MyProperty = b.MyProperty;
        b.MyProperty = (int)temp;

        Console.WriteLine(a.MyProperty);
        Console.WriteLine(b.MyProperty);



    }

    static void Main(string[] args)
    {
        Program p = new Program();
        MyInt a = new MyInt() { MyProperty = 10 };
        MyInt b = new MyInt() { MyProperty = 20 };
        p.swap<MyInt>(a, b);
        Console.WriteLine(a.MyProperty); // changed values get reflected
        Console.WriteLine(b.MyProperty); // changed values get reflected

        Console.WriteLine("Another Swap");
        object x = 10;
        object y = 20;
        p.AnotherSwap(x, y);

        Console.WriteLine(x);  // changed values are not getting  reflected
        Console.WriteLine(y);  // changed values are not getting  reflected

         Console.ReadKey();


    }
   public class MyInt
    {
        public int MyProperty { get; set; }

    }




}

Here when I am calling the swap() , though I haven’t mentioned ref , the changed values are automatically getting reflected (as in p.swap(a, b); a and b are instance of Myint and thus will by default work as ref..as per my understanding.)
But same should happen with Anotherswap() here also I am passing object x,y but now the values are not getting reflected in Main() .i.e. now its working as a value type.
Can somebody explain where my understanding is going wrong.
Let me know if u guys want more info.

Answer 1

When MyInt type is cast as Object, it gets cast as a val type. Object cannot be treated like a reference since its representing both val and ref, it must be explicitly passed by ref.

int can be cast as an object, and its still treated as a val.
string can be cast as object, and its treated as a val. Even though normally it would be a ref type.

If you did the AnotherSwap and passed T in as MyInt, you would get the same results as before. If you called the original swap algorithm with objects, you would get the same output as the latter.