Exposes the enumerator, which supports a simple iteration over a non-generic collection.
Assembly: mscorlib (in mscorlib.dll)
<[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_0_0_0%](True)> _
<[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_0_0_1%]("496B0ABE-CDEE-11d3-88E8-00902754C43A")> _
Public Interface IEnumerable
[[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_1_0_0%](true)]
[[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_1_0_1%]("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface IEnumerable
[[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_2_0_0%](true)]
[[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_2_0_1%](L"496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface class IEnumerable
[<[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_3_0_0%](true)>]
[<[%$TOPIC/h1x9x1b1_en-us_VS_110_1_0_3_0_1%]("496B0ABE-CDEE-11d3-88E8-00902754C43A")>]
type IEnumerable = interface end
The IEnumerable type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | GetEnumerator | Returns an enumerator that iterates through a collection. |
| Name | Description | |
|---|---|---|
![]() | AsParallel | Enables parallelization of a query. (Defined by ParallelEnumerable.) |
![]() | AsQueryable | Converts an IEnumerable to an IQueryable. (Defined by Queryable.) |
![]() | CastTResult | Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.) |
![]() | OfTypeTResult | Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.) |
For the generic version of this interface see System.Collections.GenericIEnumerableT.
Notes to ImplementersIEnumerable 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];
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return (IEnumerator) GetEnumerator();
}
public PeopleEnum 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;
}
object IEnumerator.Current
{
get
{
return Current;
}
}
public Person 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 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.png)