StringEnumerator.Current 属性

定义

命名空间:

System.Collections.Specialized

程序集:

System.Collections.Specialized.dll

Source:

StringCollection.cs

获取集合中的当前元素。

public:
 property System::String ^ Current { System::String ^ get(); };

public string? Current { get; }

member this.Current : string

Public ReadOnly Property Current As String

属性值

String

集合中的当前元素。

例外

InvalidOperationException

枚举器位于集合中第一个元素之前或最后一个元素之后。

示例

下面的代码示例演示 的几个属性和方法 StringEnumerator。

#using <System.dll>

using namespace System;
using namespace System::Collections::Specialized;
int main()
{
   
   // Creates and initializes a StringCollection.
   StringCollection^ myCol = gcnew StringCollection;
   array<String^>^myArr = {"red","orange","yellow","green","blue","indigo","violet"};
   myCol->AddRange( myArr );
   
   // Enumerates the elements in the StringCollection.
   StringEnumerator^ myEnumerator = myCol->GetEnumerator();
   while ( myEnumerator->MoveNext() )
      Console::WriteLine( "{0}", myEnumerator->Current );

   Console::WriteLine();
   
   // Resets the enumerator and displays the first element again.
   myEnumerator->Reset();
   if ( myEnumerator->MoveNext() )
      Console::WriteLine( "The first element is {0}.", myEnumerator->Current );
}

/*
This code produces the following output.

red
orange
yellow
green
blue
indigo
violet

The first element is red.

*/

using System;
using System.Collections.Specialized;

public class SamplesStringEnumerator  {

   public static void Main()  {

      // Creates and initializes a StringCollection.
      StringCollection myCol = new StringCollection();
      String[] myArr = new String[] { "red", "orange", "yellow", "green", "blue", "indigo", "violet" };
      myCol.AddRange( myArr );

      // Enumerates the elements in the StringCollection.
      StringEnumerator myEnumerator = myCol.GetEnumerator();
      while ( myEnumerator.MoveNext() )
         Console.WriteLine( "{0}", myEnumerator.Current );
      Console.WriteLine();

      // Resets the enumerator and displays the first element again.
      myEnumerator.Reset();
      if ( myEnumerator.MoveNext() )
         Console.WriteLine( "The first element is {0}.", myEnumerator.Current );
   }
}

/*
This code produces the following output.

red
orange
yellow
green
blue
indigo
violet

The first element is red.

*/

Imports System.Collections.Specialized

Public Class SamplesStringEnumerator

   Public Shared Sub Main()

      ' Creates and initializes a StringCollection.
      Dim myCol As New StringCollection()
      Dim myArr() As [String] = {"red", "orange", "yellow", "green", "blue", "indigo", "violet"}
      myCol.AddRange(myArr)

      ' Enumerates the elements in the StringCollection.
      Dim myEnumerator As StringEnumerator = myCol.GetEnumerator()
      While myEnumerator.MoveNext()
         Console.WriteLine("{0}", myEnumerator.Current)
      End While
      Console.WriteLine()

      ' Resets the enumerator and displays the first element again.
      myEnumerator.Reset()
      If myEnumerator.MoveNext() Then
         Console.WriteLine("The first element is {0}.", myEnumerator.Current)
      End If 

   End Sub

End Class


'This code produces the following output.
'
'red
'orange
'yellow
'green
'blue
'indigo
'violet
'
'The first element is red.

注解

创建枚举器后或调用 后 Reset ， MoveNext 必须调用 以在读取 的值 Current之前将枚举器推进到集合的第一个元素;否则为 Current 未定义。

Current 如果最后一次调用 MoveNext 返回 ， false则还会引发异常，这指示集合的末尾。

Current 不会移动枚举器的位置，并且连续调用 以 Current 返回同一对象，直到 MoveNext 调用 或 Reset 。

只要集合保持不变，枚举器就仍有效。 如果对集合进行了更改（例如添加、修改或删除元素），枚举器将不可恢复地失效，下一次InvalidOperationException调用 MoveNext 或 Reset 引发 。 如果在 和 CurrentCurrent 之间MoveNext修改集合，则返回它设置为 的元素，即使枚举器已失效。

另请参阅

• MoveNext()
• Reset()
• Current