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Dictionary<TKey, TValue>.ICollection<KeyValuePair<TKey, TValue>>.Contains Method

Determines whether the ICollection<T> contains a specific key and value.

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

bool ICollection<KeyValuePair<TKey, TValue>>.Contains(
	KeyValuePair<TKey, TValue> keyValuePair
)

Parameters

keyValuePair
Type: System.Collections.Generic.KeyValuePair<TKey, TValue>

The KeyValuePair<TKey, TValue> structure to locate in the ICollection<T>.

Return Value

Type: System.Boolean
true if keyValuePair is found in the ICollection<T>; otherwise, false.

Implements

ICollection<T>.Contains(T)

This method determines equality using the default equality comparer EqualityComparer<T>.Default for the System.Collections.Generic.KeyValuePair<TKey, TValue> structure.

This method approaches an O(1) operation.

The following code example shows how to use the System#Collections#Generic#ICollection{System#Collections#Generic#KeyValuePair{`0,`1}}#Add(KeyValuePairTKey, TValue), System#Collections#Generic#ICollection{System#Collections#Generic#KeyValuePair{`0,`1}}#Contains(KeyValuePairTKey, TValue), System#Collections#Generic#ICollection{System#Collections#Generic#KeyValuePair{`0,`1}}#CopyTo(KeyValuePairTKey, TValue, Int32), and System#Collections#Generic#ICollection{System#Collections#Generic#KeyValuePair{`0,`1}}#Remove(KeyValuePairTKey, TValue) methods of the System.Collections.Generic.ICollection<T> generic interface to manipulate a Dictionary<TKey, TValue> 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 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

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