Dictionary<TKey,TValue>.Keys 属性

定义

获取包含 Dictionary<TKey,TValue> 中的键的集合。Gets a collection containing the keys in the Dictionary<TKey,TValue>.

public:
 property System::Collections::Generic::Dictionary<TKey, TValue>::KeyCollection ^ Keys { System::Collections::Generic::Dictionary<TKey, TValue>::KeyCollection ^ get(); };
public System.Collections.Generic.Dictionary<TKey,TValue>.KeyCollection Keys { get; }
member this.Keys : System.Collections.Generic.Dictionary<'Key, 'Value>.KeyCollection
Public ReadOnly Property Keys As Dictionary(Of TKey, TValue).KeyCollection

属性值

示例

下面的代码示例演示如何使用Keys属性枚举字典中的键,以及如何枚举字典中的键和值。The following code example shows how to enumerate the keys in the dictionary using the Keys property, and how to enumerate the keys and values in the dictionary.

此代码是可以编译和执行的更大示例的一部分(openWith在本示例中使用的字典名称)。This code is part of a larger example that can be compiled and executed (openWith is the name of the Dictionary used in this example). 请参阅 Dictionary<TKey,TValue>See Dictionary<TKey,TValue>.

// To get the keys alone, use the Keys property.
Dictionary<String^, String^>::KeyCollection^ keyColl =
    openWith->Keys;

// The elements of the KeyCollection are strongly typed
// with the type that was specified for dictionary keys.
Console::WriteLine();
for each( String^ s in keyColl )
{
    Console::WriteLine("Key = {0}", s);
}
// To get the keys alone, use the Keys property.
Dictionary<string, string>.KeyCollection keyColl =
    openWith.Keys;

// The elements of the KeyCollection are strongly typed
// with the type that was specified for dictionary keys.
Console.WriteLine();
foreach( string s in keyColl )
{
    Console.WriteLine("Key = {0}", s);
}
' To get the keys alone, use the Keys property.
Dim keyColl As _
    Dictionary(Of String, String).KeyCollection = _
    openWith.Keys

' The elements of the KeyCollection are strongly typed
' with the type that was specified for dictionary keys.
Console.WriteLine()
For Each s As String In  keyColl
    Console.WriteLine("Key = {0}", s)
Next s
// When you use foreach to enumerate dictionary elements,
// the elements are retrieved as KeyValuePair objects.
Console::WriteLine();
for each( KeyValuePair<String^, String^> kvp in openWith )
{
    Console::WriteLine("Key = {0}, Value = {1}",
        kvp.Key, kvp.Value);
}
// When you use foreach to enumerate dictionary elements,
// the elements are retrieved as KeyValuePair objects.
Console.WriteLine();
foreach( KeyValuePair<string, string> kvp in openWith )
{
    Console.WriteLine("Key = {0}, Value = {1}", 
        kvp.Key, kvp.Value);
}
' When you use foreach to enumerate dictionary elements,
' the elements are retrieved as KeyValuePair objects.
Console.WriteLine()
For Each kvp As KeyValuePair(Of String, String) In openWith
    Console.WriteLine("Key = {0}, Value = {1}", _
        kvp.Key, kvp.Value)
Next kvp

注解

Dictionary<TKey,TValue>.KeyCollection键的顺序未指定,但与Values属性返回的Dictionary<TKey,TValue>.ValueCollection中的关联值顺序相同。The order of the keys in the Dictionary<TKey,TValue>.KeyCollection is unspecified, but it is the same order as the associated values in the Dictionary<TKey,TValue>.ValueCollection returned by the Values property.

返回Dictionary<TKey,TValue>.KeyCollection的不是静态副本; 相反Dictionary<TKey,TValue>.KeyCollection ,引用的是原始Dictionary<TKey,TValue>中的键。The returned Dictionary<TKey,TValue>.KeyCollection is not a static copy; instead, the Dictionary<TKey,TValue>.KeyCollection refers back to the keys in the original Dictionary<TKey,TValue>. 因此,对的Dictionary<TKey,TValue>更改将继续反映Dictionary<TKey,TValue>.KeyCollection在中。Therefore, changes to the Dictionary<TKey,TValue> continue to be reflected in the Dictionary<TKey,TValue>.KeyCollection.

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