Class Inside Structure

Question

Could some one please explain, What happens when a reference type is defined inside the value type. I write the following code:

namespace ClassInsideStruct
{
    class ClassInsideStruct
    {
        static void Main(string[] args)
        {

            ValueType ObjVal = new ValueType(10);
            ObjVal.Display();

            ValueType.ReferenceType ObjValRef = new ValueType.ReferenceType(10);
            ObjValRef.Display();

            Test(ObjVal, ObjValRef);

            ObjVal.Display();
            ObjValRef.Display();

            Console.ReadKey();

        }

        private static void Test(ValueType v, ValueType.ReferenceType r)
        {
            v.SValue = 50;
            r.RValue = 50;
        }

    }

    struct ValueType
    {

        int StructNum;
        ReferenceType ObjRef;

        public ValueType(int i)
        {
            StructNum = i;
            ObjRef = new ReferenceType(i);
        }

        public int SValue
        {
            get { return StructNum; }
            set
            {
                StructNum = value;
                ObjRef.RValue = value;
            }
        }

        public void Display()
        {
            Console.WriteLine("ValueType: " + StructNum);
            Console.Write("ReferenceType Inside ValueType Instance: ");
            ObjRef.Display();
        }

        public class ReferenceType
        {

            int ClassNum;

            public ReferenceType(int i)
            {
                ClassNum = i;
            }

            public void Display()
            {
                Console.WriteLine("Reference Type: " + ClassNum);
            }

            public int RValue
            {
                get { return ClassNum; }
                set { ClassNum = value; }
            }

        }

    }

}

Which outputs:

ValueType: 10
ReferenceType Inside ValueType Instance: Reference Type: 10
Reference Type: 10
ValueType: 10
ReferenceType Inside ValueType Instance: Reference Type: 50
Reference Type: 50

I'm curious to know, after calling the method Test(ObjVal, ObjValRef), how the values of ReferenceType is changed to 50 which resides inside the ValueType whose value is not changed?

Answer 1

I don't know for sure, but the compiler probably separates the code into a separate class and then just enforces the rules required. When you use a value type, the value is copied every time it is passed into a method. The reference to a reference type will get copied, but it refers to the same object. This same reference object will get changed while the value type that was copied will get changed. The original that you passed in will not reflect the changes on the copy.

Answer 2

Because Reference Types are Reference Types and Value Types are Value Types. No matter where they Reside.

And also Value type is not changing neither it is changing the Reference its holding. Its the Reference Type that gets changed(Read my words carefully).

i.e the underlying data at that address gets changed. The reference held by value type is still the same.