Dictionary<TKey,TValue>.IDictionary.Keys Dictionary<TKey,TValue>.IDictionary.Keys Dictionary<TKey,TValue>.IDictionary.Keys Property

定义

获取包含 ICollection 的键的 IDictionaryGets an ICollection containing the keys of the IDictionary.

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

属性值

一个 ICollection,它包含 IDictionary 的键。An ICollection containing the keys of the IDictionary.

实现

示例

下面的代码示例演示如何将IDictionary.Keys System.Collections.IDictionary接口的属性与结合Dictionary<TKey,TValue>使用,以列出字典中的键。The following code example shows how to use the IDictionary.Keys property of the System.Collections.IDictionary interface with a Dictionary<TKey,TValue>, to list the keys in the dictionary. 该示例还演示如何枚举字典中的键/值对;请注意, System.Collections.IDictionary接口的枚举器将DictionaryEntry返回对象, KeyValuePair<TKey,TValue>而不是对象。The example also shows how to enumerate the key/value pairs in the dictionary; note that the enumerator for the System.Collections.IDictionary interface returns DictionaryEntry objects rather than KeyValuePair<TKey,TValue> objects.

此代码示例摘自为IDictionary.Add方法提供的更大示例,包括输出。The code example is part of a larger example, including output, provided for the IDictionary.Add method.

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

注解

返回ICollection的中的键顺序未指定,但保证其顺序与Values属性返回的ICollection中的相应值的顺序相同。The order of the keys in the returned ICollection is unspecified, but it is guaranteed to be the same order as the corresponding values in the ICollection returned by the Values property.

获取此属性的值的运算复杂度为 O (1)。Getting the value of this property is an O(1) operation.

适用于

另请参阅