語言

HashSet<T>.Clear 方法

定義

命名空間:
System.Collections.Generic
組件:
System.Collections.dll, System.Core.dll
組件:
netstandard.dll, System.Collections.dll
組件:
System.Collections.dll
組件:
System.Core.dll
組件:
netstandard.dll
來源:
HashSet.cs
來源:
HashSet.cs
來源:
HashSet.cs
來源:
HashSet.cs
來源:
HashSet.cs

從 HashSet<T> 物件中移除所有專案。

public:
 virtual void Clear();
public void Clear();
abstract member Clear : unit -> unit
override this.Clear : unit -> unit
Public Sub Clear ()

實作

Clear()

範例

以下範例是建立並填充一個 HashSet<T> 集合，然後清除該集合並釋放該集合所參考的記憶體。

HashSet<int> Numbers = new HashSet<int>();

for (int i = 0; i < 10; i++)
{
    Numbers.Add(i);
}

Console.Write("Numbers contains {0} elements: ", Numbers.Count);
DisplaySet(Numbers);

Numbers.Clear();
Numbers.TrimExcess();

Console.Write("Numbers contains {0} elements: ", Numbers.Count);
DisplaySet(Numbers);

void DisplaySet(HashSet<int> set)
{
    Console.Write("{");
    foreach (int i in set)
    {
        Console.Write(" {0}", i);
    }
    Console.WriteLine(" }");
}

/* This example produces output similar to the following:
* Numbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
* Numbers contains 0 elements: { }
*/

let displaySet (set: HashSet<int>) =
    printf "{"

    for i in set do
        printf $" {i}"

    printfn " }"
// This example produces output similar to the following:
//     Numbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
//     Numbers contains 0 elements: { }
let numbers = HashSet<int>()

for i = 0 to 9 do
    numbers.Add i |> ignore

printf $"Numbers contains {numbers.Count} elements: "
displaySet numbers

numbers.Clear()
numbers.TrimExcess()

printf $"Numbers contains {numbers.Count} elements: "
displaySet numbers

Imports System.Collections.Generic

Class Program

    Shared Sub Main()

        Dim Numbers As HashSet(Of Integer) = New HashSet(Of Integer)()

        For i As Integer = 0 To 9
            Numbers.Add(i)
        Next i

        Console.Write("Numbers contains {0} elements: ", Numbers.Count)
        DisplaySet(Numbers)

        Numbers.Clear()
        Numbers.TrimExcess()

        Console.Write("Numbers contains {0} elements: ", Numbers.Count)
        DisplaySet(Numbers)

    End Sub
    ' This code example produces output similar to the following:
    ' Numbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
    ' Numbers contains 0 elements: { }

    Private Shared Sub DisplaySet(ByVal coll As HashSet(Of Integer))
        Console.Write("{")
        For Each i As Integer In coll
            Console.Write(" {0}", i)
        Next i
        Console.WriteLine(" }")
    End Sub

End Class

備註

Count 設為零，且集合中元素中對其他物件的參考也會被釋放。 容量保持不變，直到有人接到呼叫 TrimExcess 。

此方法是一個 O（n） 運算，其中 n 為 Count。

適用於