IEnumerable IEnumerable IEnumerable IEnumerable Interface

Definice

Zpřístupňuje enumerátor, který podporuje jednoduchou iteraci přes neobecnou kolekci.Exposes an enumerator, which supports a simple iteration over a non-generic collection.

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
Odvozené
Atributy

Příklady

Následující příklad kódu ukazuje osvědčený postup pro iteraci vlastní kolekce implementací IEnumerable rozhraní a. IEnumeratorThe following code example demonstrates the best practice for iterating a custom collection by implementing the IEnumerable and IEnumerator interfaces. V tomto příkladu nejsou členy explicitně volány, ale jsou implementovány pro podporu použití foreach (For Each v Visual Basic) pro iteraci v kolekci.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. Tento příklad je kompletní Konzolová aplikace.This example is a complete Console app. Chcete-li zkompilovat aplikaci Visual Basic, změňte spouštěcí objekt na Sub Main na stránce vlastností projektu.To compile the Visual Basic app, change the Startup object to Sub Main in the project's Properties page.

Ukázku, která ukazuje, jak implementovat IEnumerable rozhraní, naleznete v tématu implementování rozhraní IEnumerable v třídě kolekce .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

Poznámky

IEnumerableje základní rozhraní pro všechny neobecné kolekce, které lze vyčíslit.IEnumerable is the base interface for all non-generic collections that can be enumerated. Obecnou verzi tohoto rozhraní naleznete v tématu System.Collections.Generic.IEnumerable<T>.For the generic version of this interface see System.Collections.Generic.IEnumerable<T>. IEnumerableobsahuje jedinou metodu, GetEnumeratorkterá IEnumeratorvrací.IEnumerable contains a single method, GetEnumerator, which returns an IEnumerator. IEnumeratorposkytuje možnost iterovat v kolekci přidáním Current vlastností Reset a MoveNext metod.IEnumerator provides the ability to iterate through the collection by exposing a Current property and MoveNext and Reset methods.

Osvědčeným postupem je implementovat IEnumerable a IEnumerator na třídy foreach kolekce povolit syntaxi (For Each v Visual Basic), ale implementace IEnumerable není nutná.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. Pokud vaše kolekce neimplementuje IEnumerable, je stále nutné postupovat podle vzoru iterátoru pro podporu této syntaxe GetEnumerator poskytnutím metody, která vrací rozhraní, třídu nebo strukturu.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. Při použití Visual Basic je nutné zadat IEnumerator implementaci, která je vrácena nástrojem. GetEnumeratorWhen using Visual Basic, you must provide an IEnumerator implementation, which is returned by GetEnumerator. Při vývoji s C# nástrojem musíte poskytnout třídu, která obsahuje Current Reset vlastnost a MoveNext metody popsané v IEnumerator, ale třída nemusí implementovat 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.

Metody

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

Vrátí enumerátor, který iteruje kolekci.Returns an enumerator that iterates through a collection.

Metody rozšíření

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

Přetypování prvky IEnumerable na zadaný typ.Casts the elements of an IEnumerable to the specified type.

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

Filtruje prvky IEnumerable založené na zadaném typu.Filters the elements of an IEnumerable based on a specified type.

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

Povoluje paralelní zpracování dotazu.Enables parallelization of a query.

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

IEnumerable PřevedeIQueryablena.Converts an IEnumerable to an IQueryable.

Platí pro

Viz také