What is the difference between IEnumerator and IEnumerable?

Answer 1

IEnumerable

public IEnumerator GetEnumerator();

IEnumerator

public object Current;
public void Reset();
public bool MoveNext();

IEnumerable and IEnumerator are both interfaces. IEnumerable has just one method called GetEnumerator. This method retuns (as all methods return something including void) another type which is an interface and that interface is IEnumerator. When you implement enumerator logic in any of your collection class, you implement IEnumerable (either generic or non generic). IEnumerable has just one method whereas IEnumerator has 2 methods (MoveNext and Reset) and a property Current. For easy understanding consider IEnumebale a box that contains IEnumerator inside it (though not through inheritance or containment). See the code for better understanding:

class Test : IEnumerable, IEnumerator
{
     IEnumerator IEnumerable.GetEnumerator()
    {
        throw new NotImplementedException();
    }
    public object Current
    {
        get { throw new NotImplementedException(); }
    }

    public bool MoveNext()
    {
        throw new NotImplementedException();
    }
    public void Reset()
    {
        throw new NotImplementedException();
    }
}