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
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". */
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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