DictionaryEntry 结构

定义

命名空间:

System.Collections

程序集:

netstandard.dll, System.Runtime.dll

Source:

DictionaryEntry.cs

定义可以设置或检索的字典键/值对。

public value class DictionaryEntry

public struct DictionaryEntry

type DictionaryEntry = struct

Public Structure DictionaryEntry

继承

Object

ValueType

DictionaryEntry

示例

以下示例演示如何 DictionaryEntry 循环 Hashtable 访问对象。

// 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

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

重要

不建议将 DictionaryEntry 结构用于新开发。 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，请参阅不应在 GitHub 上使用 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。 由于每个元素都是键/值对，因此元素 IDictionary 类型不是键的类型或值的类型。 相反，元素类型为 DictionaryEntry. 例如：

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

该 foreach 语句是枚举器周围的包装器，它只允许从集合（而不是写入到集合）进行读取。

构造函数

名称	说明
DictionaryEntry(Object, Object)	使用指定的键和值初始化类型的实例 DictionaryEntry 。

属性

名称	说明
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

名称	说明
Deconstruct(Object, Object)	解构当前 DictionaryEntry。

另请参阅

• IDictionary
• IDictionaryEnumerator
• KeyValuePair<TKey,TValue>