IDictionary.Remove Method

Dictionary<TKey, TValue>.IDictionary.Remove Method

Removes the element with the specified key from the IDictionary.

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

void IDictionary.Remove(
	Object key


Type: System.Object

The key of the element to remove.




key is null.

This method approaches an O(1) operation.

The following code example shows how to use the IDictionary.Remove of the System.Collections.IDictionary interface with a Dictionary<TKey, TValue>.

The code example is part of a larger example, including output, provided for the IDictionary.Add method.

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
    public static void Main()
        // Create a new dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        IDictionary openWith = new Dictionary<string, string>();

        // Add some elements to the dictionary. There are no 
        // duplicate keys, but some of the values are duplicates.
        // IDictionary.Add throws an exception if incorrect types
        // are supplied for key or value.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");


// Use the Remove method to remove a key/value pair. No
// exception is thrown if the wrong data type is supplied.

if (!openWith.Contains("dib"))
    Console.WriteLine("Key \"dib\" is not found.");



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

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Community Additions

© 2015 Microsoft