Export (0) Print
Expand All

HashSet<T>.Enumerator Structure

Enumerates the elements of a HashSet<T> object.

Namespace:  System.Collections.Generic
Assembly:  System.Core (in System.Core.dll)

[SerializableAttribute]
[HostProtectionAttribute(SecurityAction.LinkDemand, MayLeakOnAbort = true)]
public struct Enumerator : IEnumerator<T>, 
	IDisposable, IEnumerator

The HashSet<T>.Enumerator generic type exposes the following members.

  NameDescription
Public propertySupported by Portable Class LibraryCurrentGets the element at the current position of the enumerator.
Top

  NameDescription
Public methodSupported by Portable Class LibraryDisposeReleases all resources used by a HashSet<T>.Enumerator object.
Public methodSupported by Portable Class LibraryEqualsIndicates whether this instance and a specified object are equal. (Inherited from ValueType.)
Public methodSupported by Portable Class LibraryGetHashCodeReturns the hash code for this instance. (Inherited from ValueType.)
Public methodSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodSupported by Portable Class LibraryMoveNextAdvances the enumerator to the next element of the HashSet<T> collection.
Public methodSupported by Portable Class LibraryToStringReturns the fully qualified type name of this instance. (Inherited from ValueType.)
Top

  NameDescription
Explicit interface implemetationPrivate propertySupported by Portable Class LibraryIEnumerator.CurrentGets the element at the current position of the enumerator.
Explicit interface implemetationPrivate methodSupported by Portable Class LibraryIEnumerator.ResetSets the enumerator to its initial position, which is before the first element in the collection.
Top

The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of 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, the Current property is undefined. Therefore, you must call the MoveNext method 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 object 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 the System.Collections.Generic namespace are not synchronized.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: MayLeakOnAbort. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show:
© 2015 Microsoft