Dictionary<TKey,TValue>.IDictionary.Keys 屬性

定義

取得 ICollection,包含 IDictionary 的索引鍵。

property System::Collections::ICollection ^ System::Collections::IDictionary::Keys { System::Collections::ICollection ^ get(); };
System.Collections.ICollection System.Collections.IDictionary.Keys { get; }
member this.System.Collections.IDictionary.Keys : System.Collections.ICollection
 ReadOnly Property Keys As ICollection Implements IDictionary.Keys

屬性值

ICollection

ICollection,包含 IDictionary 的索引鍵。

實作

範例

下列程式碼範例示範如何使用 IDictionary.Keys 介面的 System.Collections.IDictionary 屬性搭配 Dictionary<TKey,TValue> ,以列出字典中的索引鍵。 此範例也會示範如何列舉字典中的索引鍵/值組;請注意,介面的 System.Collections.IDictionary 列舉值會傳回 DictionaryEntry 物件,而不是 KeyValuePair<TKey,TValue> 物件。

程式碼範例是較大範例的一部分,包括針對 IDictionary.Add 方法提供的輸出。

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new Dictionary<string, string>();

        // Add some elements to the dictionary. There are no
        // duplicate keys, but some of the values are duplicates.
        // IDictionary.Add throws an exception if incorrect types
        // are supplied for key or value.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");
Imports System.Collections
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys,
        ' and access it using the IDictionary interface.
        '
        Dim openWith As IDictionary = _
            New Dictionary(Of String, String)
        
        ' Add some elements to the dictionary. There are no 
        ' duplicate keys, but some of the values are duplicates.
        ' IDictionary.Add throws an exception if incorrect types
        ' are supplied for key or value.
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")
// To get the keys alone, use the Keys property.
icoll = openWith.Keys;

// The elements of the collection are strongly typed
// with the type that was specified for dictionary keys,
// even though the ICollection interface is not strongly
// typed.
Console.WriteLine();
foreach( string s in icoll )
{
    Console.WriteLine("Key = {0}", s);
}
' To get the keys alone, use the Keys property.
icoll = openWith.Keys

' The elements of the collection are strongly typed
' with the type that was specified for dictionary keys,
' even though the ICollection interface is not strongly
' typed.
Console.WriteLine()
For Each s As String In  icoll
    Console.WriteLine("Key = {0}", s)
Next s
// When you use foreach to enumerate dictionary elements
// with the IDictionary interface, the elements are retrieved
// as DictionaryEntry objects instead of KeyValuePair objects.
Console.WriteLine();
foreach( DictionaryEntry de in openWith )
{
    Console.WriteLine("Key = {0}, Value = {1}",
        de.Key, de.Value);
}
' When you use foreach to enumerate dictionary elements
' with the IDictionary interface, the elements are retrieved
' as DictionaryEntry objects instead of KeyValuePair objects.
Console.WriteLine()
For Each de As DictionaryEntry In openWith
    Console.WriteLine("Key = {0}, Value = {1}", _
        de.Key, de.Value)
Next
    }
}

    End Sub

End Class

備註

未指定所 ICollection 傳回索引鍵的順序,但保證其順序與 屬性所 Values 傳回之 中的 ICollection 對應值的順序相同。

取得此屬性的值是 O (1) 作業。

適用於

另請參閱