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HybridDictionary.Contains Method

Determines whether the HybridDictionary contains a specific key.

[Visual Basic]
Public Overridable Function Contains( _
   ByVal key As Object _
) As Boolean Implements IDictionary.Contains
[C#]
public virtual bool Contains(
 object key
);
[C++]
public: virtual bool Contains(
 Object* key
);
[JScript]
public function Contains(
   key : Object
) : Boolean;

Parameters

key
The key to locate in the HybridDictionary.

Return Value

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

Implements

IDictionary.Contains

Exceptions

Exception Type Condition
ArgumentNullException key is a null reference (Nothing in Visual Basic).

Remarks

This implementation is close to O(1) in most cases.

Example

[Visual Basic, C#, C++] The following code example searches for an element in a HybridDictionary.

[Visual Basic] 
Imports System
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesHybridDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new HybridDictionary.
      Dim myCol As 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") Then
         Console.WriteLine("The collection contains the key ""Kiwis"".")
      Else
         Console.WriteLine("The collection does not contain the key ""Kiwis"".")
      End If
      Console.WriteLine()

   End Sub 'Main

   Public Shared Sub PrintKeysAndValues(myCol As IDictionary)

      Console.WriteLine("   KEY                       VALUE")
      Dim de As DictionaryEntry
      For Each de In  myCol
         Console.WriteLine("   {0,-25} {1}", de.Key, de.Value)
      Next de
      Console.WriteLine()

   End Sub 'PrintKeysAndValues

End Class 'SamplesHybridDictionary 


'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".


[C#] 
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".

*/

[C++] 
#using <mscorlib.dll>
#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;

void PrintKeysAndValues( IDictionary* myCol )  {
    Console::WriteLine( S"   KEY                       VALUE" );
    IEnumerator* myEnum = myCol->GetEnumerator();
    while (myEnum->MoveNext())
    {
        DictionaryEntry de = *__try_cast<DictionaryEntry*>(myEnum->Current);
        Console::WriteLine( S"   {0,-25} {1}", de.Key, de.Value );
    }
    Console::WriteLine();
}

int main()  {

    // Creates and initializes a new HybridDictionary.
    HybridDictionary* myCol = new HybridDictionary();
    myCol->Add( S"Braeburn Apples", S"1.49" );
    myCol->Add( S"Fuji Apples", S"1.29" );
    myCol->Add( S"Gala Apples", S"1.49" );
    myCol->Add( S"Golden Delicious Apples", S"1.29" );
    myCol->Add( S"Granny Smith Apples", S"0.89" );
    myCol->Add( S"Red Delicious Apples", S"0.99" );
    myCol->Add( S"Plantain Bananas", S"1.49" );
    myCol->Add( S"Yellow Bananas", S"0.79" );
    myCol->Add( S"Strawberries", S"3.33" );
    myCol->Add( S"Cranberries", S"5.98" );
    myCol->Add( S"Navel Oranges", S"1.29" );
    myCol->Add( S"Grapes", S"1.99" );
    myCol->Add( S"Honeydew Melon", S"0.59" );
    myCol->Add( S"Seedless Watermelon", S"0.49" );
    myCol->Add( S"Pineapple", S"1.49" );
    myCol->Add( S"Nectarine", S"1.99" );
    myCol->Add( S"Plums", S"1.69" );
    myCol->Add( S"Peaches", S"1.99" );

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

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

*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

HybridDictionary Class | HybridDictionary Members | System.Collections.Specialized Namespace | IDictionary | Performing Culture-Insensitive String Operations

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