Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All

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

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

Adds the specified value to the ICollection with the specified key.

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

void ICollection<KeyValuePair<TKey,TValue>>.Add (
	KeyValuePair<TKey,TValue> keyValuePair
)
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

keyValuePair

The KeyValuePair structure representing the key and value to add to the Dictionary.

Exception typeCondition

ArgumentNullException

The key of keyValuePair is a null reference (Nothing in Visual Basic).

ArgumentException

An element with the same key already exists in the Dictionary.

If Count is less than the capacity, this method approaches an O(1) operation. If the capacity needs to be increased to accommodate the new element, this method becomes an O(n) operation, where n is Count.

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.

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
 */

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.

.NET Framework

Supported in: 2.0

.NET Compact Framework

Supported in: 2.0
Show:
© 2015 Microsoft