DictionaryEntry 结构

  • 参考

定义

命名空间:
System.Collections
程序集:
System.Runtime.dll
程序集:
mscorlib.dll
程序集:
netstandard.dll

定义可设置或检索的字典键/值对。

public value class DictionaryEntry
public struct DictionaryEntry
[System.Serializable]
public struct DictionaryEntry
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public struct DictionaryEntry
type DictionaryEntry = struct
[<System.Serializable>]
type DictionaryEntry = struct
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type DictionaryEntry = struct
Public Structure DictionaryEntry
继承
Object
ValueType
DictionaryEntry
属性
SerializableAttribute ComVisibleAttribute

示例

以下示例演示如何使用 DictionaryEntry 来循环访问 Hashtable 对象。

// A simple example for the DictionaryEntry structure.
using namespace System;
using namespace System::Collections;

public ref class Example
{
public:
    static void Main()
    {
        // Create a new hash table.
        //
        Hashtable^ openWith = gcnew Hashtable();

        // Add some elements to the hash table. There are no
        // duplicate keys, but some of the values are duplicates.
        openWith->Add("txt", "notepad.exe");
        openWith->Add("bmp", "paint.exe");
        openWith->Add("dib", "paint.exe");
        openWith->Add("rtf", "wordpad.exe");

        // When you use foreach to enumerate hash table elements,
        // the elements are retrieved as DictionaryEntry objects.
        Console::WriteLine();
        for each (DictionaryEntry de in openWith)
        {
            Console::WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);
        }
    }
};

int main()
{
    Example::Main();
}

/* This code example produces output similar to the following:

Key = rtf, Value = wordpad.exe
Key = txt, Value = notepad.exe
Key = dib, Value = paint.exe
Key = bmp, Value = paint.exe
 */

// A simple example for the DictionaryEntry structure.
using System;
using System.Collections;

class Example
{
    public static void Main()
    {
        // Create a new hash table.
        //
        Hashtable openWith = new Hashtable();

        // Add some elements to the hash table. There are no
        // duplicate keys, but some of the values are duplicates.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");

        // When you use foreach to enumerate hash table elements,
        // the elements are retrieved as DictionaryEntry objects.
        Console.WriteLine();
        foreach (DictionaryEntry de in openWith)
        {
            Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);
        }
    }
}

/* This code example produces output similar to the following:

Key = rtf, Value = wordpad.exe
Key = txt, Value = notepad.exe
Key = dib, Value = paint.exe
Key = bmp, Value = paint.exe
 */

'A simple example for the DictionaryEntry structure.
Imports System.Collections

Module Example

    Sub Main()

        ' Create a new hash table.
        '
        Dim openWith As New Hashtable()

        ' Add some elements to the hash table. There are no
        ' duplicate keys, but some of the values are duplicates.
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")

        ' When you use For Each to enumerate hash table elements,
        ' the elements are retrieved as DictionaryEntry objects.
        Console.WriteLine()
        For Each de As DictionaryEntry In openWith
            Console.WriteLine("Key = {0}, Value = {1}", _
                de.Key, de.Value)
        Next de

    End Sub

End Module

' This code example produces output similar to the following:
'
'Key = rtf, Value = wordpad.exe
'Key = txt, Value = notepad.exe
'Key = dib, Value = paint.exe
'Key = bmp, Value = paint.exe

注解

方法 IDictionaryEnumerator.Entry 返回此类型的实例。

重要

建议不要使用 DictionaryEntry 结构进行新的开发。 相反，我们建议将泛型 KeyValuePair<TKey,TValue> 结构与 类一起使用 Dictionary<TKey,TValue> 。 有关详细信息，请参阅 GitHub 上 不应使用非泛型集合 。

C# foreach 语句和 Visual Basic For Each 语句需要集合中每个元素的类型。 由于 的每个 IDictionary 元素都是键/值对，因此元素类型不是键的类型或值的类型。 相反，元素类型为 DictionaryEntry。 例如：

for each (DictionaryEntry de in openWith)
{
    Console::WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);
}

foreach (DictionaryEntry de in openWith)
{
    Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);
}

For Each de As DictionaryEntry In openWith
    Console.WriteLine("Key = {0}, Value = {1}", _
        de.Key, de.Value)
Next de

语句 foreach 是枚举器的包装器，它只允许读取集合，而不允许写入集合。

构造函数

DictionaryEntry(Object, Object)

使用指定的键和值初始化 DictionaryEntry 类型的实例。

属性

Key

获取或设置键/值对中的键。
Value

获取或设置键/值对中的值。

方法

Deconstruct(Object, Object)

析构当前 DictionaryEntry。

适用于

另请参阅