HybridDictionary.Contains(Object) Metodo
Definizione
Importante
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Determina se l'oggetto HybridDictionary contiene una chiave specifica.
public:
virtual bool Contains(System::Object ^ key);public bool Contains (object key);abstract member Contains : obj -> bool
override this.Contains : obj -> boolPublic Function Contains (key As Object) As BooleanParametri
- key
- Object
Chiave da individuare in HybridDictionary.
Restituisce
true se la classe HybridDictionary contiene una voce con la chiave specificata; in caso contrario, false.
Implementazioni
Eccezioni
key è null.
Esempio
Nell'esempio di codice seguente viene ricercato un elemento in un HybridDictionaryoggetto .
#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintKeysAndValues( IDictionary^ myCol )
{
Console::WriteLine( " KEY VALUE" );
IEnumerator^ myEnum = myCol->GetEnumerator();
while ( myEnum->MoveNext() )
{
DictionaryEntry de = safe_cast<DictionaryEntry>(myEnum->Current);
Console::WriteLine( " {0,-25} {1}", de.Key, de.Value );
}
Console::WriteLine();
}
int main()
{
// Creates and initializes a new HybridDictionary.
HybridDictionary^ myCol = gcnew 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();
}
/*
This code produces output similar to the following:
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".
*/
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 output similar to the following:
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".
*/
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
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
End Class
'This code produces output similar to the following:
'
'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".
Commenti
Questo metodo è un'operazione O(1).
A partire da .NET Framework 2.0, questo metodo usa i metodi key e CompareTo gli oggetti Equals della raccolta per determinare se item esiste. Nelle versioni precedenti di .NET Framework questa determinazione è stata effettuata usando i Equals metodi e CompareTo del item parametro sugli oggetti dell'insieme.
Si applica a
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