using System.Collections;
class Program
{
public static void Main()
{
int[] arr = new int[10];
IEnumerator e = arr.GetEnumerator();
}
}

I think the described behavior is perfectly reasonable. arr.GetEnumerator()(s return type is actually SZArrayEnumerator. Although SZArrayEnumerator and IEnumerator<T> both implement IEnumerator, they are different types and cannot cast implicitly to each other.

You make an interesting point. I did not try casting the non-genetic enumerator to a generic one, but I am actually mildly surprised that you will get a cast exception.

Igor
PS.: A follow-up post is coming (haven’t gotten around to it yet).

A simple cast:

IEnumerator<int> e = (IEnumerator<int>)arr.GetEnumerator();
or
IEnumerator<int> e = arr.GetEnumerator() as IEnumerator<int>;

won’t have the desired effect. The former will throw a cast exception and the latter will result in e being null.

It should first be converted to Enumerable and then get the Enumerator:

IEnumerator<int> e = arr.AsEnumerable<int>().GetEnumerator();

And now I’m hoping that this is wrong and there’s an easier way, because that’s damned ugly when you think about it …

IEnumerator e = (IEnumerator)arr.GetEnumerator();
or
IEnumerator e = arr.GetEnumerator() as IEnumerator;

won’t have the desired effect. The former will throw a cast exception and the latter will result in e being null.

It should first be converted to Enumerable and then get the Enumerator:

IEnumerator e = arr.AsEnumerable().GetEnumerator();

And now I’m hoping that this is wrong and there’s an easier way, because that’s damned ugly when you think about it …

Cannot implicitly convert type ‘System.Collections.IEnumerator’ to ‘System.Collections.Generic.IEnumerator<T>’.

To make the code compilable you need to create a cast:

IEnumerator<T> e = (IEnumerator<T>) arr.GetEnumerator();

or safe cast:

IEnumerator<T> e = arr.GetEnumerator() as IEnumerator<T>