Exposes the enumerator, which supports a simple iteration over a non-generic collection.
Namespace: System.Collections
Assembly: mscorlib (in mscorlib.dll)
Visual Basic (Declaration)
<ComVisibleAttribute(True)> _
<GuidAttribute("496B0ABE-CDEE-11d3-88E8-00902754C43A")> _
Public Interface IEnumerable
Dim instance As IEnumerable
[ComVisibleAttribute(true)]
[GuidAttribute("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface IEnumerable
[ComVisibleAttribute(true)]
[GuidAttribute(L"496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface class IEnumerable
/** @attribute ComVisibleAttribute(true) */
/** @attribute GuidAttribute("496B0ABE-CDEE-11d3-88E8-00902754C43A") */
public interface IEnumerable
ComVisibleAttribute(true)
GuidAttribute("496B0ABE-CDEE-11d3-88E8-00902754C43A")
public interface IEnumerable
For the generic version of this interface see System.Collections.Generic.IEnumerable.
Notes to Implementers: IEnumerable must be implemented to support the foreach semantics of Microsoft Visual Basic. COM classes that allow enumerators also implement this interface.
The following code example demonstrates the implementation of the IEnumerable and IEnumerator interfaces for a custom collection. In this example, members of these interfaces are not explicitly called, but they are implemented to support the use of foreach (For Each in Visual Basic) to iterate through the collection.
Imports System
Imports System.Collections
Public Class Person
Public Sub New(ByVal fName As String, ByVal lName As String)
Me.firstName = fName
Me.lastName = lName
End Sub
Public firstName As String
Public lastName As String
End Class
Public Class People
Implements IEnumerable
Private _people() As Person
Public Sub New(ByVal pArray() As Person)
_people = New Person(pArray.Length - 1) {}
Dim i As Integer
For i = 0 To pArray.Length - 1
_people(i) = pArray(i)
Next i
End Sub
Public Function GetEnumerator() As IEnumerator _
Implements IEnumerable.GetEnumerator
Return New PeopleEnum(_people)
End Function
End Class
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
Class App
Shared Sub Main()
Dim peopleArray() As Person = { _
New Person("John", "Smith"), _
New Person("Jim", "Johnson"), _
New Person("Sue", "Rabon")}
Dim peopleList As New People(peopleArray)
Dim p As Person
For Each p In peopleList
Console.WriteLine(p.firstName + " " + p.lastName)
Next
End Sub
End Class
' This code produces output similar to the following:
'
' John Smith
' Jim Johnson
' Sue Rabon
using System;
using System.Collections;
public class Person
{
public Person(string fName, string lName)
{
this.firstName = fName;
this.lastName = lName;
}
public string firstName;
public string lastName;
}
public class People : IEnumerable
{
private Person[] _people;
public People(Person[] pArray)
{
_people = new Person[pArray.Length];
for (int i = 0; i < pArray.Length; i++)
{
_people[i] = pArray[i];
}
}
public IEnumerator GetEnumerator()
{
return new PeopleEnum(_people);
}
}
public class PeopleEnum : IEnumerator
{
public Person[] _people;
// Enumerators are positioned before the first element
// until the first MoveNext() call.
int position = -1;
public PeopleEnum(Person[] list)
{
_people = list;
}
public bool MoveNext()
{
position++;
return (position < _people.Length);
}
public void Reset()
{
position = -1;
}
public object Current
{
get
{
try
{
return _people[position];
}
catch (IndexOutOfRangeException)
{
throw new InvalidOperationException();
}
}
}
}
class App
{
static void Main()
{
Person[] peopleArray = new Person[3]
{
new Person("John", "Smith"),
new Person("Jim", "Johnson"),
new Person("Sue", "Rabon"),
};
People peopleList = new People(peopleArray);
foreach (Person p in peopleList)
Console.WriteLine(p.firstName + " " + p.lastName);
}
}
/* This code produces output similar to the following:
*
* John Smith
* Jim Johnson
* Sue Rabon
*
*/
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.
.NET Framework
Supported in: 3.0, 2.0, 1.1, 1.0
.NET Compact Framework
Supported in: 2.0, 1.0
XNA Framework
Supported in: 1.0