DictionaryEntry 结构

定义可设置或检索的字典键/值对。

**命名空间:**System.Collections
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Structure DictionaryEntry
用法
Dim instance As DictionaryEntry

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public struct DictionaryEntry

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public value class DictionaryEntry

/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class DictionaryEntry extends ValueType

JScript 支持使用结构，但不支持进行新的声明。

备注

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

C# 语言中的 foreach 语句（在 Visual C++ 中为 for each，在 Visual Basic 中为 For Each）需要集合中每个元素的类型。由于 IDictionary 的每个元素都是一个键/值对，因此元素类型既不是键的类型，也不是值的类型。而是 DictionaryEntry 类型。例如：

foreach (DictionaryEntry de in myHashtable) {...}

for each (DictionaryEntry^ de in myHashtable) {...}

For Each de As DictionaryEntry In myHashtable
   ...
Next de

foreach 语句是对枚举数的包装，它只允许从集合中读取，不允许写入集合。

示例

下面的示例演示如何使用 DictionaryEntry 来循环访问 Hashtable 对象。

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

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 KeyValuePair 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 = winword.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 KeyValuePair 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
 */

线程安全

此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

.NET Compact Framework

受以下版本支持：2.0、1.0

请参见

参考

DictionaryEntry 成员
System.Collections 命名空间
IDictionary
IDictionaryEnumerator
System.Collections.Generic.KeyValuePair