ListDictionary.Contains Method (Object)

 

Determines whether the ListDictionary contains a specific key.

Namespace:   System.Collections.Specialized
Assembly:  System (in System.dll)

public bool Contains(
	object key
)

Parameters

key
Type: System.Object

The key to locate in the ListDictionary.

Return Value

Type: System.Boolean

true if the ListDictionary contains an entry with the specified key; otherwise, false.

Exception Condition
ArgumentNullException

key is null.

This method is an O(n) operation, where n is Count.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on key to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

The following code example searches for an element in a ListDictionary.

using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesListDictionary  {

   public static void Main()  {

      // Creates and initializes a new ListDictionary.
      ListDictionary myCol = new ListDictionary();
      myCol.Add( "Braeburn Apples", "1.49" );
      myCol.Add( "Fuji Apples", "1.29" );
      myCol.Add( "Gala Apples", "1.49" );
      myCol.Add( "Golden Delicious Apples", "1.29" );
      myCol.Add( "Granny Smith Apples", "0.89" );
      myCol.Add( "Red Delicious Apples", "0.99" );

      // Displays the values in the ListDictionary in three different ways.
      Console.WriteLine( "Initial contents of the ListDictionary:" );
      PrintKeysAndValues( myCol );

      // Searches for a key.
      if ( myCol.Contains( "Kiwis" ) )
         Console.WriteLine( "The collection contains the key \"Kiwis\"." );
      else
         Console.WriteLine( "The collection does not contain the key \"Kiwis\"." );
      Console.WriteLine();

   }

   public static void PrintKeysAndValues( IDictionary myCol )  {
      Console.WriteLine( "   KEY                       VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.Value );
      Console.WriteLine();
   }

}


/*
This code produces the following output.

Initial contents of the ListDictionary:
   KEY                       VALUE
   Braeburn Apples           1.49
   Fuji Apples               1.29
   Gala Apples               1.49
   Golden Delicious Apples   1.29
   Granny Smith Apples       0.89
   Red Delicious Apples      0.99

The collection does not contain the key "Kiwis".

*/

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
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