Dictionary.System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Remove Method 

Note: This method is new in the .NET Framework version 2.0.

Removes a key and value from the dictionary.

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

Syntax

'Declaration
Private Function System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Remove ( _
    keyValuePair As KeyValuePair(Of TKey, TValue) _
) As Boolean Implements ICollection(Of KeyValuePair(Of TKey, TValue)).Remove
'Usage
Dim instance As Dictionary(Of TKey, TValue)
Dim keyValuePair As KeyValuePair(Of TKey, TValue)
Dim returnValue As Boolean

returnValue = CType(instance, ICollection(Of KeyValuePair(Of TKey, TValue))).Remove(keyValuePair)
bool ICollection<KeyValuePair<TKey,TValue>>.Remove (
    KeyValuePair<TKey,TValue> keyValuePair
)
private:
virtual bool System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Remove (
    KeyValuePair<TKey, TValue> keyValuePair
) sealed = ICollection<KeyValuePair<TKey, TValue>>::Remove
J# supports the use of explicit interface implementations, but not the declaration of new ones.
JScript supports the use of explicit interface implementations, but not the declarations of new ones.

Parameters

Return Value

true if the key and value represented by keyValuePair is successfully found and removed; otherwise, false. This method returns false if keyValuePair is not found in the ICollection.

Remarks

This method uses Comparer to determine equality for the key, and the default equality comparer EqualityComparer.Default to determine equality for the value.

This method approaches an O(1) operation.

Example

The following code example shows how to use the System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Add, System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Contains, System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.CopyTo, and System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey,TValue>>.Remove methods of the System.Collections.Generic.ICollection generic interface to manipulate a Dictionary object.

Imports System
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys, and
        ' access it through the generic ICollection interface. The
        ' generic ICollection interface views the dictionary as a
        ' collection of KeyValuePair objects with the same type
        ' arguments as the dictionary.
        '
        Dim openWith As ICollection(Of KeyValuePair(Of String, String)) _
            = New Dictionary(Of String, String)
        
        ' Add some elements to the dictionary. When elements are 
        ' added through the ICollection(Of T) interface, the keys
        ' and values must be wrapped in KeyValuePair objects.
        '
        openWith.Add(New KeyValuePair(Of String,String)("txt", "notepad.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("bmp", "paint.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("dib", "paint.exe"))
        openWith.Add(New KeyValuePair(Of String,String)("rtf", "wordpad.exe"))
        
        Console.WriteLine()
        For Each element As KeyValuePair(Of String, String) in openWith
            Console.WriteLine("{0, {1", element.Key, element.Value)
        Next
           
        ' The Contains method also takes a KeyValuePair object.
        '
        Console.WriteLine(vbLf & _
            "Contains(KeyValuePair(""txt"", ""notepad.exe"")): {0", _
            openWith.Contains(New KeyValuePair(Of String,String)("txt", "notepad.exe")))

        ' The Remove method takes a KeyValuePair object.)
        '
        ' Use the Remove method to remove a key/value pair.
        Console.WriteLine(vbLf &  _
            "Remove(New KeyValuePair(""dib"", ""paint.exe""))")
        openWith.Remove(New KeyValuePair(Of String,String)("dib", "paint.exe"))
        
        Console.WriteLine()
        For Each element As KeyValuePair(Of String, String) in openWith
            Console.WriteLine("{0, {1", element.Key, element.Value)
        Next

        ' Create an array of KeyValuePair objects and copy the 
        ' contents of the dictionary to it. Subtract one from the
        ' array size because Visual Basic allocates an extra array
        ' element.
        Dim copy(openWith.Count - 1) As KeyValuePair(Of String, String)
        openWith.CopyTo(copy, 0)
    
        ' List the contents of the array.
        '
        Console.WriteLine()
        For Each element As KeyValuePair(Of String, String) in copy
            Console.WriteLine("{0, {1", element.Key, element.Value)
        Next

    End Sub

End Class

' This code example produces the following output:
'
'txt, notepad.exe
'bmp, paint.exe
'dib, paint.exe
'rtf, wordpad.exe
'
'Contains(KeyValuePair("txt", "notepad.exe")): True
'
'Remove(New KeyValuePair("dib", "paint.exe"))
'
'txt, notepad.exe
'bmp, paint.exe
'rtf, wordpad.exe
'
'txt, notepad.exe
'bmp, paint.exe
'rtf, wordpad.exe 
using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys, and
        // access it through the generic ICollection interface. The
        // generic ICollection interface views the dictionary as a
        // collection of KeyValuePair objects with the same type
        // arguments as the dictionary.
        //
        ICollection<KeyValuePair<String, String>> openWith =
            new Dictionary<String, String>();
        
        // Add some elements to the dictionary. When elements are 
        // added through the ICollection<T> interface, the keys
        // and values must be wrapped in KeyValuePair objects.
        //
        openWith.Add(new KeyValuePair<String,String>("txt", "notepad.exe"));
        openWith.Add(new KeyValuePair<String,String>("bmp", "paint.exe"));
        openWith.Add(new KeyValuePair<String,String>("dib", "paint.exe"));
        openWith.Add(new KeyValuePair<String,String>("rtf", "wordpad.exe"));
        
        Console.WriteLine();
        foreach( KeyValuePair<string, string> element in openWith )
        {
            Console.WriteLine("{0, {1", element.Key, element.Value);
        
           
        // The Contains method also takes a KeyValuePair object.
        //
        Console.WriteLine(
            "\nContains(KeyValuePair(\"txt\", \"notepad.exe\")): {0", 
            openWith.Contains(new KeyValuePair<String,String>("txt", "notepad.exe")));

        // The Remove method takes a KeyValuePair object.)
        //
        // Use the Remove method to remove a key/value pair.
        Console.WriteLine("\nRemove(new KeyValuePair(\"dib\", \"paint.exe\"))");
        openWith.Remove(new KeyValuePair<String,String>("dib", "paint.exe"));
        
        Console.WriteLine();
        foreach( KeyValuePair<string, string> element in openWith )
        {
            Console.WriteLine("{0, {1", element.Key, element.Value);
        

        // Create an array of KeyValuePair objects and copy the 
        // contents of the dictionary to it. 
        // 
        KeyValuePair<string, string>[] copy = 
            new KeyValuePair<string, string>[openWith.Count];
        openWith.CopyTo(copy, 0);
    
        // List the contents of the array.
        //
        Console.WriteLine();
        foreach( KeyValuePair<string, string> element in copy )
        {
            Console.WriteLine("{0, {1", element.Key, element.Value);
        
    


/* This code example produces the following output:

txt, notepad.exe
bmp, paint.exe
dib, paint.exe
rtf, wordpad.exe

Contains(KeyValuePair("txt", "notepad.exe")): True

Remove(new KeyValuePair("dib", "paint.exe"))

txt, notepad.exe
bmp, paint.exe
rtf, wordpad.exe

txt, notepad.exe
bmp, paint.exe
rtf, wordpad.exe
 */

Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

Version Information

.NET Framework

Supported in: 2.0

.NET Compact Framework

Supported in: 2.0

See Also

Reference

Dictionary Generic Class
Dictionary Members
System.Collections.Generic Namespace