IEnumerable IEnumerable IEnumerable IEnumerable Interface


非ジェネリック コレクションに対する単純な反復処理をサポートする列挙子を公開します。Exposes an enumerator, which supports a simple iteration over a non-generic collection.

public interface class IEnumerable
public interface IEnumerable
type IEnumerable = interface
Public Interface IEnumerable

次のコード例は、実装することで、カスタム コレクションを反復処理するためのベスト プラクティスを示します、IEnumerableIEnumeratorインターフェイス。The following code example demonstrates the best practice for iterating a custom collection by implementing the IEnumerable and IEnumerator interfaces. この例では、これらのインターフェイスのメンバーは明示的に呼び出されないの使用をサポートするために実装されるforeach(For Each Visual Basic で) コレクションを反復処理します。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. この例では、完全なコンソール アプリです。This example is a complete Console app. Visual Basic アプリをコンパイルするには、変更、スタートアップ オブジェクトSub Mainプロジェクトのプロパティページ。To compile the Visual Basic app, change the Startup object to Sub Main in the project's Properties page.

実装する方法を示すサンプルについては、IEnumerableインターフェイスは、「コレクション クラスで IEnumerable インターフェイスを実装します。For 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()
        return (position < _people.Length);

    public void Reset()
        position = -1;

    object IEnumerator.Current
            return Current;

    public Person Current
                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
                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)

    End Sub
End Class

' This code produces output similar to the following:
' John Smith
' Jim Johnson
' Sue Rabon


IEnumerable すべての非ジェネリック コレクションを列挙できますが、基本インターフェイスです。IEnumerable is the base interface for all non-generic collections that can be enumerated. このインターフェイスのジェネリック バージョンについては、次を参照してください。System.Collections.Generic.IEnumerable<T>します。For the generic version of this interface see System.Collections.Generic.IEnumerable<T>. IEnumerable 1 つのメソッドを含むGetEnumerator、返された、IEnumeratorします。IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumerator 公開することで、コレクションを反復処理する機能を提供するCurrentプロパティとMoveNextResetメソッド。IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

実装することをお勧めIEnumerableIEnumerator有効にし、コレクション クラスに、 foreach (For Each Visual Basic で) 構文を実装するただしIEnumerableは必要ありません。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. コレクションが実装していない場合IEnumerable、提供することで、この構文をサポートする反復子パターンを利用する必要がありますが、GetEnumeratorインターフェイス、クラスまたは構造体を返すメソッド。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. Visual Basic を使用しているときは指定する必要があります、 IEnumerator 、実装によって返されるGetEnumeratorします。When using Visual Basic, you must provide an IEnumerator implementation, which is returned by GetEnumerator. C# で開発して、含むクラスを指定する必要がありますと、Currentプロパティ、およびMoveNextResetメソッドによる記述でIEnumerator、クラスが実装する必要はありませんが、IEnumeratorします。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.


GetEnumerator() GetEnumerator() GetEnumerator() GetEnumerator()

コレクションを反復処理する列挙子を返します。Returns an enumerator that iterates through a collection.

Extension Methods

Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable)

IEnumerable の要素を、指定した型にキャストします。Casts the elements of an IEnumerable to the specified type.

OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable)

指定された型に基づいて IEnumerable の要素をフィルター処理します。Filters the elements of an IEnumerable based on a specified type.

AsParallel(IEnumerable) AsParallel(IEnumerable) AsParallel(IEnumerable) AsParallel(IEnumerable)

クエリの並列化を有効にします。Enables parallelization of a query.

AsQueryable(IEnumerable) AsQueryable(IEnumerable) AsQueryable(IEnumerable) AsQueryable(IEnumerable)

IEnumerableIQueryable に変換します。Converts an IEnumerable to an IQueryable.