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Is there a built-in way to convert IEnumerator<T> to IEnumerable<T>?
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An IEnumerator is a thing that can enumerate: it has the Current property and the MoveNext and Reset methods (which in . NET code you probably won't call explicitly, though you could). An IEnumerable is a thing that can be enumerated...which simply means that it has a GetEnumerator method that returns an IEnumerator .
Here is the documentation on IEnumerator . They are used to get the values of lists, where the length is not necessarily known ahead of time (even though it could be). The word comes from enumerate , which means "to count off or name one by one".
The C# GetEnumerator() method is used to convert string object into char enumerator. It returns instance of CharEnumerator. So, you can iterate string through loop.
IEnumerable is an interface defining a single method GetEnumerator() that returns an IEnumerator interface. This works for readonly access to a collection that implements that IEnumerable can be used with a foreach statement. IEnumerator has two methods MoveNext and Reset. It also has a property called Current.
The easiest way of converting I can think of is via the yield statement
public static IEnumerable<T> ToIEnumerable<T>(this IEnumerator<T> enumerator) { while ( enumerator.MoveNext() ) { yield return enumerator.Current; } } compared to the list version this has the advantage of not enumerating the entire list before returning an IEnumerable. using the yield statement you'd only iterate over the items you need, whereas using the list version, you'd first iterate over all items in the list and then all the items you need.
for a little more fun you could change it to
public static IEnumerable<K> Select<K,T>(this IEnumerator<T> e, Func<K,T> selector) { while ( e.MoveNext() ) { yield return selector(e.Current); } } you'd then be able to use linq on your enumerator like:
IEnumerator<T> enumerator; var someList = from item in enumerator select new classThatTakesTInConstructor(item); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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