ReferenceValueTypes.cs

void Main()
{
	var a = new A(1);
	var b = new B(2);
	
	Console.WriteLine("Value of A: {0}", a.Value);
	Console.WriteLine("Value of B: {0}", b.Value);
	
	ChangeA(a);
	Console.WriteLine("Value of A: {0}", a.Value);
	
	ChangeARef(ref a);
	Console.WriteLine("Value of A: {0}", a.Value);
	
	ChangeAValue(a);
	Console.WriteLine("Value of A: {0}", a.Value);
	
	ChangeB(b);
	Console.WriteLine("Value of B: {0}", b.Value);
	
	ChangeBRef(ref b);
	Console.WriteLine("Value of B: {0}", b.Value);
}

void ChangeA(A a)
{
	Console.WriteLine("ChangeA");
	a = new A(3);
}

void ChangeARef(ref A a)
{
	Console.WriteLine("ChangeARef");
	a = new A(4);
}

void ChangeAValue(A a)
{
	Console.WriteLine("ChangeAValue");
	a.Value = 5;
}

void ChangeB(B b)
{
	Console.WriteLine("ChangeB");
	b.Value = 6;
}

void ChangeBRef(ref B b)
{
	Console.WriteLine("ChangeBRef");
	
	b = new B(7);
}

class A
{
	public A(int value)
	{
		Value = value;
	}
	
	public int Value { get; set; }
}

struct B
{
	public int Value;
	
	public B(int value)
	{
		Value = value;
	}
}

Result when this program is run:

Value of A: 1
Value of B: 2
ChangeA
Value of A: 1
ChangeARef
Value of A: 4
ChangeAValue
Value of A: 5
ChangeB
Value of B: 2
ChangeBRef
Value of B: 7