IEnumerable IEnumerable IEnumerable IEnumerable Interface

Definition

public interface class IEnumerable

[System.Runtime.InteropServices.ComVisible(true)]
[System.Runtime.InteropServices.Guid("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface IEnumerable

type IEnumerable = interface

Public Interface IEnumerable

Derived

Microsoft.Build.BuildEngine.BuildItemGroupMicrosoft.Build.BuildEngine.BuildItemGroupMicrosoft.Build.BuildEngine.BuildItemGroupMicrosoft.Build.BuildEngine.BuildItemGroup

Microsoft.Build.BuildEngine.BuildItemGroupCollectionMicrosoft.Build.BuildEngine.BuildItemGroupCollectionMicrosoft.Build.BuildEngine.BuildItemGroupCollectionMicrosoft.Build.BuildEngine.BuildItemGroupCollection

Microsoft.Build.BuildEngine.BuildPropertyGroupMicrosoft.Build.BuildEngine.BuildPropertyGroupMicrosoft.Build.BuildEngine.BuildPropertyGroupMicrosoft.Build.BuildEngine.BuildPropertyGroup

Microsoft.Build.BuildEngine.BuildPropertyGroupCollectionMicrosoft.Build.BuildEngine.BuildPropertyGroupCollectionMicrosoft.Build.BuildEngine.BuildPropertyGroupCollectionMicrosoft.Build.BuildEngine.BuildPropertyGroupCollection

Microsoft.Build.BuildEngine.ImportCollectionMicrosoft.Build.BuildEngine.ImportCollectionMicrosoft.Build.BuildEngine.ImportCollectionMicrosoft.Build.BuildEngine.ImportCollection

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Attributes

ComVisibleAttribute GuidAttribute

Examples

Im folgenden Codebeispiel wird veranschaulicht, die bewährte Methode für das Durchlaufen einer benutzerdefinierten Sammlung durch die Implementierung der IEnumerable und IEnumerator Schnittstellen.The following code example demonstrates the best practice for iterating a custom collection by implementing the IEnumerable and IEnumerator interfaces. In diesem Beispiel Member dieser Schnittstellen nicht explizit aufgerufen, aber sie werden zur Unterstützung der Verwendung von implementiert foreach (For Each in Visual Basic) zum Durchlaufen der Auflistung.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. In diesem Beispiel wird eine vollständige Konsolen-app.This example is a complete Console app. Zum Kompilieren der Visual Basic-app ändern Sie die Startobjekt zu Sub Main des Projekts Eigenschaften Seite.To compile the Visual Basic app, change the Startup object to Sub Main in the project’s Properties page.

Ein Beispiel, das zeigt, wie Sie implementieren die IEnumerable Schnittstelle, finden Sie unter implementieren die IEnumerable-Schnittstelle in einer AuflistungsklasseFor a sample that shows how to implement the IEnumerable interface, see Implementing the IEnumerable Interface in a Collection Class

using System;
using System.Collections;

// Simple business object.
public class Person
{
    public Person(string fName, string lName)
    {
        this.firstName = fName;
        this.lastName = lName;
    }

    public string firstName;
    public string lastName;
}

// Collection of Person objects. This class
// implements IEnumerable so that it can be used
// with ForEach syntax.
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];
        }
    }

// Implementation for the GetEnumerator method.
    IEnumerator IEnumerable.GetEnumerator()
    {
       return (IEnumerator) GetEnumerator();
    }

    public PeopleEnum GetEnumerator()
    {
        return new PeopleEnum(_people);
    }
}

// When you implement IEnumerable, you must also implement IEnumerator.
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
 *
 */

Imports System
Imports System.Collections

' Simple business object.
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

' Collection of Person objects, which implements IEnumerable so that
' it can be used with ForEach syntax.
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

    ' Implementation of GetEnumerator.
    Public Function GetEnumerator() As IEnumerator _
      Implements IEnumerable.GetEnumerator

        Return New PeopleEnum(_people)
    End Function

End Class

' When you implement IEnumerable, you must also implement IEnumerator.
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

Remarks

IEnumerable ist die Basisschnittstelle für alle nicht generischen Auflistungen, die aufgelistet werden können.IEnumerable is the base interface for all non-generic collections that can be enumerated. Die generische Version dieser Schnittstelle finden Sie unter System.Collections.Generic.IEnumerable<T>.For the generic version of this interface see System.Collections.Generic.IEnumerable<T>. IEnumerable enthält eine einzelne Methode, GetEnumerator, gibt ein IEnumerator.IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumerator bietet die Möglichkeit zum Durchlaufen der Auflistung durch Bereitstellen einer Current Eigenschaft und MoveNext und Reset Methoden.IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

Es ist eine bewährte Methode zum Implementieren IEnumerable und IEnumerator auf Ihre Auflistungsklassen aktivieren die foreach (For Each in Visual Basic) Syntax jedoch implementieren IEnumerable ist nicht erforderlich.It is a best practice to implement IEnumerable and IEnumerator on your collection classes to enable the foreach (For Each in Visual Basic) syntax, however implementing IEnumerable is not required. Wenn Ihre Sammlung keine implementiert IEnumerable, folgen Sie weiterhin das iteratormuster, um diese Syntax unterstützt wird, durch die Bereitstellung einer GetEnumerator Methode, die eine Schnittstelle, Klasse oder Struktur zurückgibt.If your collection does not implement IEnumerable, you must still follow the iterator pattern to support this syntax by providing a GetEnumerator method that returns an interface, class or struct. Wenn Sie Visual Basic verwenden zu können, müssen Sie angeben einer IEnumerator -Implementierung, die von zurückgegeben wird GetEnumerator.When using Visual Basic, you must provide an IEnumerator implementation, which is returned by GetEnumerator. Wenn mit c# entwickeln muss Geben Sie eine Klasse mit einer Current -Eigenschaft, und MoveNext und Reset Methoden wie beschrieben IEnumerator, aber die Klasse keinen implementieren IEnumerator.When developing with C# you must provide a class that contains a Current property, and MoveNext and Reset methods as described by IEnumerator, but the class does not have to implement IEnumerator.

Methods

Applies to

See Also

• IEnumerator IEnumerator IEnumerator IEnumerator
• IEnumerable<T>
• Iteratoren (C# und Visual Basic) Iterators (C# and Visual Basic)
• Implementieren die IEnumerable-Schnittstelle in einer Auflistungsklasse Implementing the IEnumerable Interface in a Collection Class