Queue<T>::Enumerator Structure
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Enumerates the elements of a Queue<T>.
Assembly: System (in System.dll)
The Queue<T>::Enumerator generic type exposes the following members.
| Name | Description | |
|---|---|---|
 | Dispose | Releases all resources used by the Queue<T>::Enumerator. |
| Equals | Indicates whether this instance and a specified object are equal. (Inherited from ValueType.) |
 | Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode | Returns the hash code for this instance. (Inherited from ValueType.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| MoveNext | Advances the enumerator to the next element of the Queue<T>. |
| ToString | Returns the fully qualified type name of this instance. (Inherited from ValueType.) |
| Name | Description | |
|---|---|---|
  | IEnumerator::Current | Gets the element at the current position of the enumerator. |
 | IEnumerator::Reset | Sets the enumerator to its initial position, which is before the first element in the collection. |
The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of the enumerators. Therefore, using foreach is recommended, instead of directly manipulating the enumerator.
Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.
Initially, the enumerator is positioned before the first element in the collection. At this position, Current is undefined. Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.
Current returns the same object until MoveNext is called. MoveNext sets Current to the next element.
If MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. When the enumerator is at this position, subsequent calls to MoveNext also return false. If the last call to MoveNext returned false, Current is undefined. You cannot set Current to the first element of the collection again; you must create a new enumerator instance instead.
An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.
The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
Default implementations of collections in System.Collections.Generic are not synchronized.