ApplicationDomainCollection.System.Collections.IEnumerable.GetEnumerator Method

2007-12-12

Returns an enumerator that iterates through the collection.

Namespace: Microsoft.Web.Administration
Assembly: Microsoft.Web.Administration (in microsoft.web.administration.dll)

Syntax

'Declaration
Private Function System.Collections.IEnumerable.GetEnumerator As IEnumerator Implements IEnumerable.GetEnumerator
'Usage
Dim instance As ApplicationDomainCollection
Dim returnValue As IEnumerator

returnValue = CType(instance, IEnumerable).GetEnumerator

IEnumerator IEnumerable.GetEnumerator ()

private:
virtual IEnumerator^ System.Collections.IEnumerable.GetEnumerator () sealed = IEnumerable::GetEnumerator

Not applicable.

Return Value

An IEnumerator that can be used to iterate through the collection.

Remarks

The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of the enumerators. Therefore, the foreach statement 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. Reset also brings the enumerator back to this position. 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 you read the value of Current.

The Current property returns the same object until either MoveNext or Reset 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. To set Current to the first element of the collection again, you can call Reset followed by MoveNext.

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 whole enumeration. To let the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

This method is an O(1) operation.

Platforms

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

Version Information

.NET Framework

Supported in: 3.0

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