Question

Is this the only way of passing a List to a method and editing that List, without modifying the original List?

class CopyTest1
{
    List<int> _myList = new List<int>();
    public CopyTest1(List<int> l)
    {
        foreach (int num in l)
        {
            _myList.Add(num);
        }
        _myList.RemoveAt(0); // no effect on original List
    }
}

Answer 1

duplicate the list:

_myLocalList = new List<int>(_myList);

and perform the operations on the local list.