HybridDictionary.Clear HybridDictionary.Clear HybridDictionary.Clear HybridDictionary.Clear Method

Definition

Removes all entries from the HybridDictionary.

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

Implements

Examples

The following code example adds to and removes elements from a HybridDictionary.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintKeysAndValues( IDictionary^ myCol )
{
   Console::WriteLine( "   KEY                       VALUE" );
   IEnumerator^ myEnum = myCol->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      DictionaryEntry de =  safe_cast<DictionaryEntry>(myEnum->Current);
      Console::WriteLine( "   {0,-25} {1}", de.Key, de.Value );
   }

   Console::WriteLine();
}

int main()
{
   
   // Creates and initializes a new HybridDictionary.
   HybridDictionary^ myCol = gcnew HybridDictionary;
   myCol->Add( "Braeburn Apples", "1.49" );
   myCol->Add( "Fuji Apples", "1.29" );
   myCol->Add( "Gala Apples", "1.49" );
   myCol->Add( "Golden Delicious Apples", "1.29" );
   myCol->Add( "Granny Smith Apples", "0.89" );
   myCol->Add( "Red Delicious Apples", "0.99" );
   myCol->Add( "Plantain Bananas", "1.49" );
   myCol->Add( "Yellow Bananas", "0.79" );
   myCol->Add( "Strawberries", "3.33" );
   myCol->Add( "Cranberries", "5.98" );
   myCol->Add( "Navel Oranges", "1.29" );
   myCol->Add( "Grapes", "1.99" );
   myCol->Add( "Honeydew Melon", "0.59" );
   myCol->Add( "Seedless Watermelon", "0.49" );
   myCol->Add( "Pineapple", "1.49" );
   myCol->Add( "Nectarine", "1.99" );
   myCol->Add( "Plums", "1.69" );
   myCol->Add( "Peaches", "1.99" );
   
   // Displays the values in the HybridDictionary in three different ways.
   Console::WriteLine( "Initial contents of the HybridDictionary:" );
   PrintKeysAndValues( myCol );
   
   // Deletes a key.
   myCol->Remove( "Plums" );
   Console::WriteLine( "The collection contains the following elements after removing \"Plums\":" );
   PrintKeysAndValues( myCol );
   
   // Clears the entire collection.
   myCol->Clear();
   Console::WriteLine( "The collection contains the following elements after it is cleared:" );
   PrintKeysAndValues( myCol );
}

/*
This code produces the following output.

Initial contents of the HybridDictionary:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

The collection contains the following elements after removing "Plums":
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Navel Oranges             1.29
   Fuji Apples               1.29

The collection contains the following elements after it is cleared:
   KEY                       VALUE

*/
using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesHybridDictionary  {

   public static void Main()  {

      // Creates and initializes a new HybridDictionary.
      HybridDictionary myCol = new HybridDictionary();
      myCol.Add( "Braeburn Apples", "1.49" );
      myCol.Add( "Fuji Apples", "1.29" );
      myCol.Add( "Gala Apples", "1.49" );
      myCol.Add( "Golden Delicious Apples", "1.29" );
      myCol.Add( "Granny Smith Apples", "0.89" );
      myCol.Add( "Red Delicious Apples", "0.99" );
      myCol.Add( "Plantain Bananas", "1.49" );
      myCol.Add( "Yellow Bananas", "0.79" );
      myCol.Add( "Strawberries", "3.33" );
      myCol.Add( "Cranberries", "5.98" );
      myCol.Add( "Navel Oranges", "1.29" );
      myCol.Add( "Grapes", "1.99" );
      myCol.Add( "Honeydew Melon", "0.59" );
      myCol.Add( "Seedless Watermelon", "0.49" );
      myCol.Add( "Pineapple", "1.49" );
      myCol.Add( "Nectarine", "1.99" );
      myCol.Add( "Plums", "1.69" );
      myCol.Add( "Peaches", "1.99" );

      // Displays the values in the HybridDictionary in three different ways.
      Console.WriteLine( "Initial contents of the HybridDictionary:" );
      PrintKeysAndValues( myCol );

      // Deletes a key.
      myCol.Remove( "Plums" );
      Console.WriteLine( "The collection contains the following elements after removing \"Plums\":" );
      PrintKeysAndValues( myCol );

      // Clears the entire collection.
      myCol.Clear();
      Console.WriteLine( "The collection contains the following elements after it is cleared:" );
      PrintKeysAndValues( myCol );

   }

   public static void PrintKeysAndValues( IDictionary myCol )  {
      Console.WriteLine( "   KEY                       VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.Value );
      Console.WriteLine();
   }

}

/*
This code produces the following output.

Initial contents of the HybridDictionary:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

The collection contains the following elements after removing "Plums":
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Navel Oranges             1.29
   Fuji Apples               1.29

The collection contains the following elements after it is cleared:
   KEY                       VALUE

*/
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesHybridDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new HybridDictionary.
      Dim myCol As New HybridDictionary()
      myCol.Add("Braeburn Apples", "1.49")
      myCol.Add("Fuji Apples", "1.29")
      myCol.Add("Gala Apples", "1.49")
      myCol.Add("Golden Delicious Apples", "1.29")
      myCol.Add("Granny Smith Apples", "0.89")
      myCol.Add("Red Delicious Apples", "0.99")
      myCol.Add("Plantain Bananas", "1.49")
      myCol.Add("Yellow Bananas", "0.79")
      myCol.Add("Strawberries", "3.33")
      myCol.Add("Cranberries", "5.98")
      myCol.Add("Navel Oranges", "1.29")
      myCol.Add("Grapes", "1.99")
      myCol.Add("Honeydew Melon", "0.59")
      myCol.Add("Seedless Watermelon", "0.49")
      myCol.Add("Pineapple", "1.49")
      myCol.Add("Nectarine", "1.99")
      myCol.Add("Plums", "1.69")
      myCol.Add("Peaches", "1.99")

      ' Displays the values in the HybridDictionary in three different ways.
      Console.WriteLine("Initial contents of the HybridDictionary:")
      PrintKeysAndValues(myCol)

      ' Deletes a key.
      myCol.Remove("Plums")
      Console.WriteLine("The collection contains the following elements after removing ""Plums"":")
      PrintKeysAndValues(myCol)

      ' Clears the entire collection.
      myCol.Clear()
      Console.WriteLine("The collection contains the following elements after it is cleared:")
      PrintKeysAndValues(myCol)

   End Sub 'Main

   Public Shared Sub PrintKeysAndValues(myCol As IDictionary)

      Console.WriteLine("   KEY                       VALUE")
      Dim de As DictionaryEntry
      For Each de In  myCol
         Console.WriteLine("   {0,-25} {1}", de.Key, de.Value)
      Next de
      Console.WriteLine()

   End Sub 'PrintKeysAndValues

End Class 'SamplesHybridDictionary 


'This code produces the following output.
'
'Initial contents of the HybridDictionary:
'   KEY                       VALUE
'   Seedless Watermelon       0.49
'   Nectarine                 1.99
'   Cranberries               5.98
'   Plantain Bananas          1.49
'   Honeydew Melon            0.59
'   Pineapple                 1.49
'   Strawberries              3.33
'   Grapes                    1.99
'   Braeburn Apples           1.49
'   Peaches                   1.99
'   Red Delicious Apples      0.99
'   Golden Delicious Apples   1.29
'   Yellow Bananas            0.79
'   Granny Smith Apples       0.89
'   Gala Apples               1.49
'   Plums                     1.69
'   Navel Oranges             1.29
'   Fuji Apples               1.29
'
'The collection contains the following elements after removing "Plums":
'   KEY                       VALUE
'   Seedless Watermelon       0.49
'   Nectarine                 1.99
'   Cranberries               5.98
'   Plantain Bananas          1.49
'   Honeydew Melon            0.59
'   Pineapple                 1.49
'   Strawberries              3.33
'   Grapes                    1.99
'   Braeburn Apples           1.49
'   Peaches                   1.99
'   Red Delicious Apples      0.99
'   Golden Delicious Apples   1.29
'   Yellow Bananas            0.79
'   Granny Smith Apples       0.89
'   Gala Apples               1.49
'   Navel Oranges             1.29
'   Fuji Apples               1.29
'
'The collection contains the following elements after it is cleared:
'   KEY                       VALUE
'

Remarks

Count is set to zero, and references to other objects from elements of the collection are also released.

If the collection is already stored in a Hashtable, the collection remains in the Hashtable.

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

Applies to

See also