IGrouping<TKey,TElement>.Key 属性

定义

命名空间:

System.Linq

程序集:

System.Linq.dll

获取 IGrouping<TKey,TElement> 的键。

public:
 property TKey Key { TKey get(); };

public TKey Key { get; }

member this.Key : 'Key

Public ReadOnly Property Key As TKey

属性值

TKey

IGrouping<TKey,TElement> 的键。

示例

以下示例演示如何使用 Key 属性标记 IGrouping<TKey,TElement> 对象序列 IGrouping<TKey,TElement> 中的每个对象。 方法 GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) 用于获取对象的序列 IGrouping<TKey,TElement> 。 foreach然后，在 Visual C# 或 For Each Visual Basic 循环中循环访问每个IGrouping<TKey,TElement>对象，输出其键及其包含的值数。

// Get a sequence of IGrouping objects.
IEnumerable<IGrouping<System.Reflection.MemberTypes, System.Reflection.MemberInfo>> memberQuery =
    typeof(String).GetMembers().
    GroupBy(member => member.MemberType);

// Output the key of each IGrouping object and the count of values.
foreach (IGrouping<System.Reflection.MemberTypes, System.Reflection.MemberInfo> group in memberQuery)
    Console.WriteLine("(Key) {0} (Member count) {1}", group.Key, group.Count());

// The output is similar to:
// (Key) Method (Member count) 113
// (Key) Constructor (Member count) 8
// (Key) Property (Member count) 2
// (Key) Field (Member count) 1

' Get a sequence of IGrouping objects.
Dim memberQuery As  _
IEnumerable(Of IGrouping(Of System.Reflection.MemberTypes, System.Reflection.MemberInfo)) = _
    Type.GetType("String").GetMembers(). _
    GroupBy(Function(ByVal member) member.MemberType)

' Output the key of each IGrouping object and the count of values.
For Each group As  _
IGrouping(Of System.Reflection.MemberTypes, System.Reflection.MemberInfo) In memberQuery
    MsgBox(String.Format("(Key) {0} (Member count) {1}", group.Key, group.Count()))
Next

' The output is similar to:
' (Key) Method (Member count) 113
' (Key) Constructor (Member count) 8
' (Key) Property (Member count) 2
' (Key) Field (Member count) 1

注解

的 IGrouping<TKey,TElement> 键表示 中每个值通用的属性 IGrouping<TKey,TElement>。