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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
)

Parameters

key
Type: System.Object

The key of the element to remove.

Implements

IDictionary.Remove(Object)

ExceptionCondition
ArgumentNullException

key is null.

NotSupportedException

The Hashtable is read-only.

-or-

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 );
      Console.WriteLine();
   }

}


/*
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

*/

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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