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Hashtable.Remove Method

Removes the element with the specified key from the Hashtable.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)

public virtual void Remove(
	Object key


Type: System.Object

The key of the element to remove.




key is null.


The Hashtable is read-only.


The Hashtable has a fixed size.

If the Hashtable does not contain an element with the specified key, the Hashtable remains unchanged. No exception is thrown.

This method is an O(1) operation.

The following example shows how to remove elements from the Hashtable.

using System;
using System.Collections;
public class SamplesHashtable  {

   public static void Main()  {

      // Creates and initializes a new Hashtable.
      Hashtable myHT = new Hashtable();
      myHT.Add( "1a", "The" );
      myHT.Add( "1b", "quick" );
      myHT.Add( "1c", "brown" );
      myHT.Add( "2a", "fox" );
      myHT.Add( "2b", "jumped" );
      myHT.Add( "2c", "over" );
      myHT.Add( "3a", "the" );
      myHT.Add( "3b", "lazy" );
      myHT.Add( "3c", "dog" );

      // Displays the Hashtable.
      Console.WriteLine( "The Hashtable initially contains the following:" );
      PrintKeysAndValues( myHT );

      // Removes the element with the key "3b".
      myHT.Remove( "3b" );

      // Displays the current state of the Hashtable.
      Console.WriteLine( "After removing \"lazy\":" );
      PrintKeysAndValues( myHT );

   public static void PrintKeysAndValues( Hashtable myHT )  {
      foreach ( DictionaryEntry de in myHT )
         Console.WriteLine( "    {0}:    {1}", de.Key, de.Value );


This code produces the following output.

The Hashtable initially contains the following:
    2c:    over
    3a:    the
    2b:    jumped
    3b:    lazy
    1b:    quick
    3c:    dog
    2a:    fox
    1c:    brown
    1a:    The

After removing "lazy":
    2c:    over
    3a:    the
    2b:    jumped
    1b:    quick
    3c:    dog
    2a:    fox
    1c:    brown
    1a:    The


Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0