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HybridDictionary.Contains Method

Determines whether the HybridDictionary contains a specific key.

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

public bool Contains (
	Object key
)
public final boolean Contains (
	Object key
)
public final function Contains (
	key : Object
) : boolean
Not applicable.

Parameters

key

The key to locate in the HybridDictionary.

Return Value

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

Exception typeCondition

ArgumentNullException

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

This method is an O(1) operation.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on item 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 HybridDictionary.

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

public class SamplesHybridDictionary  {

   public static void Main()  {

      // Creates and initializes a new HybridDictionary.
      HybridDictionary myCol = new HybridDictionary();
      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" );
      myCol.Add( "Plantain Bananas", "1.49" );
      myCol.Add( "Yellow Bananas", "0.79" );
      myCol.Add( "Strawberries", "3.33" );
      myCol.Add( "Cranberries", "5.98" );
      myCol.Add( "Navel Oranges", "1.29" );
      myCol.Add( "Grapes", "1.99" );
      myCol.Add( "Honeydew Melon", "0.59" );
      myCol.Add( "Seedless Watermelon", "0.49" );
      myCol.Add( "Pineapple", "1.49" );
      myCol.Add( "Nectarine", "1.99" );
      myCol.Add( "Plums", "1.69" );
      myCol.Add( "Peaches", "1.99" );

      // Displays the values in the HybridDictionary in three different ways.
      Console.WriteLine( "Initial contents of the HybridDictionary:" );
      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 HybridDictionary:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

The collection does not contain the key "Kiwis".

*/

import System.*;
import System.Collections.*;
import System.Collections.Specialized.*;

public class SamplesHybridDictionary
{
    public static void main(String[] args)
    {
        // Creates and initializes a new HybridDictionary.
        HybridDictionary myCol = new HybridDictionary();
        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");
        myCol.Add("Plantain Bananas", "1.49");
        myCol.Add("Yellow Bananas", "0.79");
        myCol.Add("Strawberries", "3.33");
        myCol.Add("Cranberries", "5.98");
        myCol.Add("Navel Oranges", "1.29");
        myCol.Add("Grapes", "1.99");
        myCol.Add("Honeydew Melon", "0.59");
        myCol.Add("Seedless Watermelon", "0.49");
        myCol.Add("Pineapple", "1.49");
        myCol.Add("Nectarine", "1.99");
        myCol.Add("Plums", "1.69");
        myCol.Add("Peaches", "1.99");
          
        // Displays the values in the HybridDictionary in three different ways.
        Console.WriteLine("Initial contents of the HybridDictionary:");
        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();
    }//main
        
    public static void PrintKeysAndValues(IDictionary myCol) 
    {
        IEnumerator objEnum = myCol.GetEnumerator();
        Console.WriteLine("   KEY                       VALUE");
        while (objEnum.MoveNext()) {
            DictionaryEntry de = (DictionaryEntry)objEnum.get_Current();
            Console.WriteLine("   {0,-25} {1}", de.get_Key(), de.get_Value());
        }
        Console.WriteLine();
    } //PrintKeysAndValues
} //SamplesHybridDictionary
 
/*
Initial contents of the HybridDictionary:
   KEY                       VALUE
   Strawberries              3.33
   Yellow Bananas            0.79
   Cranberries               5.98
   Grapes                    1.99
   Granny Smith Apples       0.89
   Seedless Watermelon       0.49
   Honeydew Melon            0.59
   Red Delicious Apples      0.99
   Navel Oranges             1.29
   Fuji Apples               1.29
   Plantain Bananas          1.49
   Gala Apples               1.49
   Pineapple                 1.49
   Plums                     1.69
   Braeburn Apples           1.49
   Peaches                   1.99
   Golden Delicious Apples   1.29
   Nectarine                 1.99

The collection does not contain the key "Kiwis".

*/

Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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