List passed by ref - help me explain this behaviour

Question

Take a look at the following program:

class Test
{
    List myList = new List();

    public void TestMethod()
    {
        myList.Add         


        

Answer 1

Use the ref keyword.

Look at the definitive reference here to understand passing parameters.
To be specific, look at this, to understand the behavior of the code.

EDIT: Sort works on the same reference (that is passed by value) and hence the values are ordered. However, assigning a new instance to the parameter won't work because parameter is passed by value, unless you put ref.

Putting ref lets you change the pointer to the reference to a new instance of List in your case. Without ref, you can work on the existing parameter, but can't make it point to something else.