moveNext

MoveNext is a method used by enumerator objects to advance to the next element in a collection. It returns a boolean indicating whether a next element exists.

In .NET, MoveNext is defined by the interfaces System.Collections.IEnumerator and System.Collections.Generic.IEnumerator<T>. It advances the enumerator to the next element; if successful, the Current property holds the element, otherwise there is no current element and the enumeration has ended. At initialization, the enumerator is positioned before the first element, and MoveNext must be called to advance to the first element.

Usage typically involves obtaining an enumerator from a collection and repeatedly calling MoveNext in a loop, retrieving the element from Current each time. For example, while (enumerator.MoveNext()) { var item = enumerator.Current; } However, most code uses foreach, which abstracts away the explicit MoveNext call.

Modifying the underlying collection during enumeration can invalidate the enumerator, and MoveNext may throw an InvalidOperationException if the collection has been changed. The Reset method is part of the interface but is not always supported; some implementations throw NotSupportedException when Reset is called.

MoveNext is central to the iterator pattern used by yield return in languages like C#, where the compiler generates a state machine that advances via MoveNext. An asynchronous variant, MoveNextAsync, is used by IAsyncEnumerator in asynchronous sequences.