IEnumerator.Current IEnumerator.Current IEnumerator.Current IEnumerator.Current Property

定義

取得集合中位於列舉值目前位置的元素。Gets the element in the collection at the current position of the enumerator.

public:
 property System::Object ^ Current { System::Object ^ get(); };
public object Current { get; }
member this.Current : obj
Public ReadOnly Property Current As Object

屬性值

位於列舉值中目前位置的集合中的元素。The element in the collection at the current position of the enumerator.

範例

下列程式碼範例示範如何執行IEnumerator自訂集合的介面。The following code example demonstrates the implementation of the IEnumerator interfaces for a custom collection. 在此範例中Current , 不會明確呼叫, 但會實作為支援foreach使用 (for each在 Visual Basic 中)。In this example, Current is not explicitly called, but it is implemented to support the use of foreach (for each in Visual Basic). 這個程式碼範例是IEnumerator介面之較大範例的一部分。This code example is part of a larger example for the IEnumerator interface.

// 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();
            }
        }
    }
}
' 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

備註

Current在下列任一情況下都未定義:Current is undefined under any of the following conditions:

  • 枚舉器位於集合中的第一個元素之前, 緊接在建立枚舉器之後。The enumerator is positioned before the first element in the collection, immediately after the enumerator is created. MoveNext在讀取的值Current之前, 必須呼叫以將枚舉器前移至集合的第一個元素。MoveNext must be called to advance the enumerator to the first element of the collection before reading the value of Current.

  • 最後一次呼叫MoveNextfalse傳回, 指出集合的結尾。The last call to MoveNext returned false, which indicates the end of the collection.

  • 因為集合中所做的變更, 例如新增、修改或刪除元素, 所以列舉值會無效。The enumerator is invalidated due to changes made in the collection, such as adding, modifying, or deleting elements.

Current 會傳回相同的物件直到呼叫 MoveNextCurrent returns the same object until MoveNext is called. MoveNext 會將 Current 設定為下一個項目。MoveNext sets Current to the next element.

適用於

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