In my c# app, I've got a list that I navigate with an Enumerator. It works great for moving forward through the list, but the Enumerator class doesn't have a MoveBack method.
Is there different class that has a MoveBack method, or do I need to write my own?
Any enumerators using the IEnumerator interface by definition must start before the first element and iterate forwards through the collection. In short: they don't support backwards traversal.
If you want backwards traversal you'll need to write your own enumeration functions that allow you start anywhere you want.
You could reverse the list and interate over that. Or, with some classes, you could do a for loop from end to beginning and use ElementAt().
Sometimes I had to deal with such a situation with certain C++ STL containers that only provide a forward iterator. If you know in advance how many elements backwards you need to go, you might do something like this:
IEnumerator<int> e1 = yourListOfInt.GetEnumerator();
IEnumerator<int> e2 = e1;
for (int i = 0; i < 3; ++i) e2.MoveNext();
Now e1 is three elements ahead of e2. That was the only solution I had in C++ some years ago.
But if you're using a list, I assume you may access it by index?
