IEnumerable Interfaz

Definición

Espacio de nombres:
System.Collections
Ensamblado:
System.Runtime.dll
Ensamblado:
mscorlib.dll
Ensamblado:
netstandard.dll

Expone un enumerador, que admite una iteración simple en una colección no genérica.Exposes an enumerator, which supports a simple iteration over a non-generic collection.

public interface class IEnumerable
public interface IEnumerable
[System.Runtime.InteropServices.Guid("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
public interface 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
Atributos
ComVisibleAttribute GuidAttribute

Ejemplos

En el ejemplo de código siguiente se muestra el procedimiento recomendado para recorrer en iteración una colección personalizada mediante la implementación de las interfaces IEnumerable y IEnumerator.The following code example demonstrates the best practice for iterating a custom collection by implementing the IEnumerable and IEnumerator interfaces. En este ejemplo, no se llama a los miembros de estas interfaces 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. Este ejemplo es una aplicación de consola completa.This example is a complete Console app. Para compilar la aplicación Visual Basic, cambie el objeto startup a Sub Main en la página de propiedades del proyecto.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 interfaz de IEnumerable, vea implementar la interfaz IEnumerable en una clase de colección .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()
    {
        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.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 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 solo método, GetEnumerator, que devuelve una IEnumerator.IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumerator proporciona la capacidad de recorrer en iteración la colección exponiendo una propiedad Current y métodos MoveNext y Reset.IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

Se recomienda implementar IEnumerable y IEnumerator en las clases de colección para habilitar la sintaxis de foreach (For Each en Visual Basic), pero no es necesario implementar IEnumerable.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 admitir esta sintaxis proporcionando un método GetEnumerator que devuelva 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 utilizar Visual Basic, debe proporcionar una implementación de IEnumerator, devuelta 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 contenga una propiedad Current y métodos MoveNext y Reset 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

GetEnumerator()

Devuelve un enumerador que recorre en iteración una colección.Returns an enumerator that iterates through a collection.

Métodos de extensión

Cast<TResult>(IEnumerable)

Convierte los elementos de IEnumerable en el tipo especificado.Casts the elements of an IEnumerable to the specified type.
OfType<TResult>(IEnumerable)

Filtra los elementos de IEnumerable en función de un tipo especificado.Filters the elements of an IEnumerable based on a specified type.
AsParallel(IEnumerable)

Habilita la paralelización de una consulta.Enables parallelization of a query.
AsQueryable(IEnumerable)

Convierte una interfaz IEnumerable en IQueryable.Converts an IEnumerable to an IQueryable.

Se aplica a

Consulte también: