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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 example shows how to use explicit interface implementations 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 Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // 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"));

      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in openWith)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }

      // The Contains method also takes a KeyValuePair object.
      //
      outputBlock.Text += String.Format(
          "\nContains(KeyValuePair(\"txt\", \"notepad.exe\")): {0}",
          openWith.Contains(new KeyValuePair<String, String>("txt", "notepad.exe"))) + "\n";

      // The Remove method takes a KeyValuePair object.)
      //
      // Use the Remove method to remove a key/value pair.
      outputBlock.Text += String.Format("\nRemove(new KeyValuePair(\"dib\", \"paint.exe\"))") + "\n";
      openWith.Remove(new KeyValuePair<String, String>("dib", "paint.exe"));

      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in openWith)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }

      // 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.
      //
      outputBlock.Text += "\n";
      foreach (KeyValuePair<string, string> element in copy)
      {
         outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
      }
   }
}

/* 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
 */


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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