Advances the enumerator to the next element of the collection.
Assembly: mscorlib (in mscorlib.dll)
The collection was modified after the enumerator was created.
After an enumerator is created or after the Reset method is called, an enumerator is positioned before the first element of the collection, and the first call to the method moves the enumerator over the first element of the collection.
If passes the end of the collection, the enumerator is positioned after the last element in the collection and returns false. When the enumerator is at this position, subsequent calls to also return false until Reset is called.
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 or Reset throws an InvalidOperationException.
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
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.