IEnumerable 介面

定義

命名空間:: System.Collections

組件:: mscorlib.dll, System.Runtime.dll

組件:: netstandard.dll, System.Runtime.dll

組件:: System.Runtime.dll

組件:: mscorlib.dll

組件:: netstandard.dll

來源:: IEnumerable.cs

來源:: IEnumerable.cs

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

公開列舉值，其支援非泛型集合的簡單反覆專案。

public interface class IEnumerable

public interface IEnumerable

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

[System.Runtime.InteropServices.Guid("496B0ABE-CDEE-11d3-88E8-00902754C43A")]
[System.Runtime.InteropServices.ComVisible(true)]
public interface IEnumerable

type IEnumerable = interface

[<System.Runtime.InteropServices.Guid("496B0ABE-CDEE-11d3-88E8-00902754C43A")>]
type IEnumerable = interface

[<System.Runtime.InteropServices.Guid("496B0ABE-CDEE-11d3-88E8-00902754C43A")>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type IEnumerable = interface

Public Interface IEnumerable

衍生: Microsoft.Extensions.AI.AdditionalPropertiesDictionary<TValue>

Microsoft.Extensions.AI.AIFunctionArguments

Microsoft.Extensions.AI.GeneratedEmbeddings<TEmbedding>

Microsoft.Extensions.Configuration.Memory.MemoryConfigurationProvider

Microsoft.Extensions.DependencyInjection.IServiceCollection

更多…

屬性: GuidAttribute ComVisibleAttribute

範例

以下程式碼範例展示了透過實作 IEnumerable and IEnumerator 介面來迭代自訂集合的最佳實務。在此範例中，這些介面的成員並未被明確呼叫，但它們實作以支援在 VisualFor Each Basic 中以foreach遍歷集合。此範例是完整的控制台應用程式。要編譯 Visual Basic 應用程式，請在專案的屬性頁面將啟動物件改為子主（Sub Main）。

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

備註

IEnumerable 是所有可列舉的非通用集合的基礎介面。關於此介面的通用版本，請參見 System.Collections.Generic.IEnumerable<T>。 IEnumerable 包含一個單一方法， GetEnumerator回傳一個 IEnumerator。 IEnumerator提供透過揭露Current屬性與MoveNext Reset方法來遍歷集合的能力。

最佳實作IEnumerable是IEnumerator對你的集合類別啟用（For Each在 Visual Basic 中）語foreach法，但實作IEnumerable並非必須。如果你的集合沒有實作 IEnumerable，你仍必須遵循迭代器模式來支援此語法，提供 GetEnumerator 一個回傳介面、類別或結構的方法。使用 Visual Basic 時，必須提供 IEnumerator 實作，該實作由 GetEnumerator返回。使用 C# 開發時，必須提供一個包含Current屬性和MoveNextReset方法IEnumerator的類別，但該類別不必實作 IEnumerator。

方法

名稱	Description
GetEnumerator()	傳回逐一查看集合的列舉值。

擴充方法

名稱	Description
AsParallel(IEnumerable)	啟用查詢的平行處理。
AsQueryable(IEnumerable)	將 IEnumerable 轉換成 IQueryable。
Cast<TResult>(IEnumerable)	將 IEnumerable 的項目轉換成指定的型別。
OfType<TResult>(IEnumerable)	根據指定的型別篩選 IEnumerable 的專案。

適用於

另請參閱

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共用方式為

IEnumerable 介面

定義

範例

備註

方法

擴充方法

適用於

另請參閱

意見反應