Initialization list to constructor

Question

I'm working on an assignment in school where we are supposed to make a constructor to our own List-class that takes an initialization list as an argument.

This is what I want to be able to do:

List ourList {1, 2, 3};

This is what I have so far:

List::List(std::initializer_list<int> il)
{
  head_ = copy(il.begin(), il.end());
}

List_Node* List::copy(std::initializer_list<int>::iterator begin,
                      std::initializer_list<int>::iterator end)
{
  if(begin == end)
    return nullptr;

  List_Node* new_list = new List_Node(*begin);

  List_Node* node = copy(begin++, end);
  new_list->next_ = node;
  return new_list;
}

In my humble opinion, this should work great. However, when I try my initialization (List list {1,2,3};) I get a seg-fault. Could someone please explain what it is I'm doing wrong here?

Answer 1

List_Node* node = copy(begin++, end);

This will call copy again with the same arguments, recursing forever and never completing.

You should have been able to tell this by using a debugger to see where it crashed, and you would have seen that there were hundreds of calls to List::copy, not the three calls you expected.

You want ++begin not begin++