HashSet<T>.Clear Method

Definition

Removes all elements from a HashSet<T> object.

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

Implements

Examples

The following example creates and populates a HashSet<T> collection, then clears it and releases the memory referenced by the collection.

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: { }
*/
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: { }

Remarks

Count is set to zero and references to other objects from elements of the collection are also released. The capacity remains unchanged until a call to TrimExcess is made.

This method is an O(n) operation, where n is Count.

Applies to