Sets the enumerator to its initial position, which is before the first element in the collection.
Assembly: mscorlib (in mscorlib.dll)
The collection was modified after the enumerator was created.
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 the next call to the MoveNext or method throws an InvalidOperationException.
The method is provided for COM interoperability. It does not necessarily need to be implemented; instead, the implementer can simply throw a NotSupportedException.Notes to Implementers
All calls to must result in the same state for the enumerator. The preferred implementation is to move the enumerator to the beginning of the collection, before the first element. This invalidates the enumerator if the collection has been modified since the enumerator was created, which is consistent with MoveNext and Current.
The following code example demonstrates the implementation of the IEnumerator interfaces for a custom collection. In this example, is not explicitly called, but it is implemented to support the use of foreach (for each in Visual Basic). This code example is part of a larger example for the IEnumerator interface.
Public Class PeopleEnum Implements IEnumerator Public _people() As Person ' Enumerators are positioned before the first element ' until the first MoveNext() call. Dim position As Integer = -1 Public Sub New(ByVal list() As Person) _people = list End Sub Public Function MoveNext() As Boolean Implements IEnumerator.MoveNext position = position + 1 Return (position < _people.Length) End Function Public Sub Reset() Implements IEnumerator.Reset position = -1 End Sub Public ReadOnly Property Current() As Object Implements IEnumerator.Current Get Try Return _people(position) Catch ex As IndexOutOfRangeException Throw New InvalidOperationException() End Try End Get End Property End Class
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2