IEnumerator.Reset 方法

public:
 void Reset();

public void Reset();

abstract member Reset : unit -> unit

Public Sub Reset ()

例外

示例

下面的代码示例演示自定义集合接口的 IEnumerator 实现。 在此示例中， Reset 未显式调用，但它实现为支持在 Visual Basic 中使用 foreach （for each 在 Visual Basic 中）。 此代码示例是接口的较大示例的 IEnumerator 一部分。

// 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

注解

如果对集合进行了更改（例如添加、修改或删除元素），则行为 Reset 是未定义的。

为 Reset COM 互操作性提供了该方法。 它不一定需要实现;相反，实现者只需引发一个 NotSupportedException。

实施者说明

对 Reset() 枚举器的所有调用都必须产生相同的状态。 首选实现是在第一个元素之前将枚举器移到集合的开头。 如果自创建枚举器后已修改集合（与枚举器一致且Current一MoveNext()致），则这会使枚举器失效。

另请参阅

• MoveNext()
• Current