Editing Iterator (section)

===.NET===
Iterators in the [[.NET Framework]] (i.e. C#) are called "enumerators" and represented by the <code>IEnumerator</code> interface.<ref name=Albahari>{{cite book |last=Albahari |first=Joseph |title= C# 10 in a Nutshell |date=2022 |publisher= O'Reilly |isbn= 978-1-098-12195-2}}</ref>{{rp|189–190, 344}}<ref name=Skeet>{{cite book |last=Skeet|first=Jon|title= C# in Depth |date=23 March 2019 |publisher= Manning |isbn= 978-1617294532}}</ref>{{rp|53–54}}<code>IEnumerator</code> provides a <code>MoveNext()</code> method, which advances to the next element and indicates whether the end of the collection has been reached;<ref name=Albahari/>{{rp|344}}<ref name=Skeet/>{{rp|55–56}}<ref name=Price>{{cite book |last=Price | first=Mark J. |title=C# 8.0 and .NET Core 3.0 – Modern Cross-Platform Development: Build Applications with C#, .NET Core, Entity Framework Core, ASP.NET Core, and ML.NET Using Visual Studio Code | publisher= Packt |isbn= 978-1-098-12195-2}}</ref>{{rp|89}} a <code>Current</code> property, to obtain the value of the element currently being pointed at.<ref name=Albahari/>{{rp|344}}<ref name=Skeet/>{{rp|56}}<ref name=Price/>{{rp|89}} and an optional <code>Reset()</code> method,<ref name=Albahari/>{{rp|344}} to rewind the enumerator back to its initial position. The enumerator initially points to a special value before the first element, so a call to <code>MoveNext()</code> is required to begin iterating.

Enumerators are typically obtained by calling the <code>GetEnumerator()</code> method of an object implementing the <code>IEnumerable</code> interface.<ref name=Skeet/>{{rp|54–56}}<ref name=Price/>{{rp|54–56}} a <code>Current</code> property, to obtain the value of the element currently being pointed at;<ref name=Albahari/>{{rp|344}}<ref name=Skeet/>{{rp|56}}<ref name=Price/>{{rp|89}}Container classes typically implement this interface. However, the [[foreach]] statement in [[C Sharp (programming language)|C#]] can operate on any object providing such a method, even if it does not implement <code>IEnumerable</code> ([[duck typing]]).<ref name=Price/>{{rp|89}} Both interfaces were expanded into [[generic programming|generic]] versions in [[.NET Framework#.NET Framework 2.0|.NET 2.0]].

The following shows a simple use of iterators in C# 2.0:

<syntaxhighlight lang="csharp">
// explicit version
IEnumerator<MyType> iter = list.GetEnumerator();
while (iter.MoveNext())
    Console.WriteLine(iter.Current);

// implicit version
foreach (MyType value in list)
    Console.WriteLine(value);
</syntaxhighlight>

C# 2.0 also supports [[#Generators|generators]]: a method that is declared as returning <code>IEnumerator</code> (or <code>IEnumerable</code>), but uses the "<code>yield return</code>" statement to produce a sequence of elements instead of returning an object instance, will be transformed by the compiler into a new class implementing the appropriate interface.