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IEnumerable interface

 

Date de publication : novembre 2016

Expose un énumérateur, qui prend en charge une itération simple sur une collection non générique.

Pour parcourir le code source de .NET Framework pour ce type, consultez la Source de référence.

Espace de noms:   System.Collections
Assembly:  mscorlib (dans mscorlib.dll)

[GuidAttribute("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
[ComVisibleAttribute(true)]
public interface IEnumerable

NomDescription
System_CAPS_pubmethodGetEnumerator()

Retourne un énumérateur qui itère au sein d'une collection.

NomDescription
System_CAPS_pubmethodAsParallel()

Surchargé. Active la parallélisation d'une requête.(Défini par ParallelEnumerable.)

System_CAPS_pubmethodAsQueryable()

Surchargé. Convertit un IEnumerable à un IQueryable.(Défini par Queryable.)

System_CAPS_pubmethodCast<TResult>()

Convertit les éléments d’un IEnumerable au type spécifié.(Défini par Enumerable.)

System_CAPS_pubmethodOfType<TResult>()

Filtre les éléments d’un IEnumerable basé sur un type spécifié.(Défini par Enumerable.)

System_CAPS_noteRemarque

To view the .NET Framework source code for this type, see the Reference Sourcehttp://referencesource.microsoft.com/#mscorlib/system/collections/ienumerable.cs#9be451ac13d86a97. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructionshttp://referencesource.microsoft.com/.

IEnumerable is the base interface for all non-generic collections that can be enumerated. For the generic version of this interface see System.Collections.Generic.IEnumerable<T>. IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

It is a best practice to implement T:System.Collections.IEnumerable and T:System.Collections.IEnumerator on your collection classes to enable the foreach (For Each in Visual Basic) syntax, however implementing T:System.Collections.IEnumerable is not required. If your collection does not implement T:System.Collections.IEnumerable, you must still follow the iterator pattern to support this syntax by providing a GetEnumerator method that returns an interface, class or struct. When using Visual Basic, you must provide an T:System.Collections.IEnumerator implementation, which is returned by GetEnumerator. When developing with C# you must provide a class that contains a Current property, and MoveNext and Reset methods as described by T:System.Collections.IEnumerator, but the class does not have to implement T:System.Collections.IEnumerator.

The following code example demonstrates the best practice for iterating a custom collection by implementing the T:System.Collections.IEnumerable and T:System.Collections.IEnumerator interfaces. 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. This example is a complete Console app. To compile the Visual Basic app, change the Startup object to Sub Main in the project’s Properties page.

For a sample that shows how to implement the T:System.Collections.IEnumerable interface, see Implementing the IEnumerable Interface in a Collection Classhttp://code.msdn.microsoft.com/Implementing-the-e1708a24

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
 *
 */

Plateforme Windows universelle
Disponible depuis 8
.NET Framework
Disponible depuis 1.1
Bibliothèque de classes portable
Pris en charge dans : plateformes .NET portables
Silverlight
Disponible depuis 2.0
Silverlight pour Windows Phone
Disponible depuis 7.0
Windows Phone
Disponible depuis 8.1
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