IEnumerable IEnumerable IEnumerable IEnumerable Interface

Definición

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

Derivado

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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Atributos

ComVisibleAttribute GuidAttribute

Ejemplos

En el ejemplo de código siguiente se muestra el procedimiento recomendado para recorrer en iteración una colección personalizada implementando la IEnumerable y IEnumerator interfaces.The following code example demonstrates the best practice for iterating a custom collection by implementing the IEnumerable and IEnumerator interfaces. En este ejemplo, los miembros de estas interfaces no se llama explícitamente, pero se implementan para admitir el uso de foreach (For Each en Visual Basic) para recorrer en iteración la colección.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. En este ejemplo es una aplicación de consola completa.This example is a complete Console app. Para compilar la aplicación de Visual Basic, cambie el objeto Startup a Sub Main en el proyecto propiedades página.To compile the Visual Basic app, change the Startup object to Sub Main in the project's Properties page.

Para obtener un ejemplo que muestra cómo implementar la IEnumerable interfaz, vea implementa la interfaz IEnumerable en una clase de colecciónFor 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

Comentarios

IEnumerable es la interfaz base para todas las colecciones no genéricas que se pueden enumerar.IEnumerable is the base interface for all non-generic collections that can be enumerated. Para obtener la versión genérica de esta interfaz, vea System.Collections.Generic.IEnumerable<T>.For the generic version of this interface see System.Collections.Generic.IEnumerable<T>. IEnumerable contiene un método único, GetEnumerator, que devuelve un IEnumerator.IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumerator proporciona la capacidad de recorrer en iteración la colección mediante la exposición de un Current propiedad y MoveNext y Reset métodos.IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

Es una práctica recomendada para implementar IEnumerable y IEnumerator en sus clases de colección para habilitar el foreach (For Each en Visual Basic) sintaxis, pero implementar IEnumerable no es necesario.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. Si la colección no implementa IEnumerable, debe seguir el patrón de iterador para que admita esta sintaxis proporcionando un GetEnumerator método que devuelve una interfaz, clase o struct.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. Al usar Visual Basic, debe proporcionar un IEnumerator implementación, que es devuelto por GetEnumerator.When using Visual Basic, you must provide an IEnumerator implementation, which is returned by GetEnumerator. Al desarrollar con C# debe proporcionar una clase que contiene un Current propiedad, y MoveNext y Reset métodos como se describe en IEnumerator, pero la clase no tiene que implementar 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.

Métodos

Extension Methods

Se aplica a

Consulte también:

• IEnumerator IEnumerator IEnumerator IEnumerator
• IEnumerable<T>
• Iteradores (C# y Visual Basic)Iterators (C# and Visual Basic)
• Implementar la interfaz IEnumerable en una clase de colecciónImplementing the IEnumerable Interface in a Collection Class