Dictionary<TKey,TValue>.IDictionary.Contains(Object) Dictionary<TKey,TValue>.IDictionary.Contains(Object) Dictionary<TKey,TValue>.IDictionary.Contains(Object) Method

Definizione

Determina se IDictionary contiene un elemento con la chiave specificata.Determines whether the IDictionary contains an element with the specified key.

 virtual bool System.Collections.IDictionary.Contains(System::Object ^ key) = System::Collections::IDictionary::Contains;
bool IDictionary.Contains (object key);
Function Contains (key As Object) As Boolean Implements IDictionary.Contains

Parametri

key
Object Object Object

Chiave da individuare in IDictionary.The key to locate in the IDictionary.

Restituisce

true se IDictionary contiene un elemento con la chiave specificata; in caso contrario, false.true if the IDictionary contains an element with the specified key; otherwise, false.

Implementazioni

Eccezioni

Esempi

Il codice seguente viene illustrato come utilizzare il IDictionary.Contains metodo per il System.Collections.IDictionary interfacciarsi con un Dictionary<TKey,TValue>.The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a Dictionary<TKey,TValue>. Nell'esempio viene illustrato che il metodo restituisce false se viene fornita una chiave del tipo di dati non corretto.The example demonstrates that the method returns false if a key of the wrong data type is supplied.

L'esempio di codice fa parte di un esempio più esaustivo, incluso l'output, fornito per il IDictionary.Add (metodo).The code example is part of a larger example, including output, provided for the IDictionary.Add method.

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new Dictionary<string, string>();

        // Add some elements to the dictionary. There are no 
        // duplicate keys, but some of the values are duplicates.
        // IDictionary.Add throws an exception if incorrect types
        // are supplied for key or value.
        openWith.Add("txt", "notepad.exe");
        openWith.Add("bmp", "paint.exe");
        openWith.Add("dib", "paint.exe");
        openWith.Add("rtf", "wordpad.exe");
Imports System
Imports System.Collections
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys,
        ' and access it using the IDictionary interface.
        '
        Dim openWith As IDictionary = _
            New Dictionary(Of String, String)
        
        ' Add some elements to the dictionary. There are no 
        ' duplicate keys, but some of the values are duplicates.
        ' IDictionary.Add throws an exception if incorrect types
        ' are supplied for key or value.
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")
// Contains can be used to test keys before inserting 
// them.
if (!openWith.Contains("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}", 
        openWith["ht"]);
}

// IDictionary.Contains returns false if the wrong data
// type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}",
    openWith.Contains(29.7));
' Contains can be used to test keys before inserting 
' them.
If Not openWith.Contains("ht") Then
    openWith.Add("ht", "hypertrm.exe")
    Console.WriteLine("Value added for key = ""ht"": {0}", _
        openWith("ht"))
End If

' IDictionary.Contains returns False if the wrong data 
' type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}", _
    openWith.Contains(29.7))
    }
}

    End Sub

End Class

Commenti

Questo metodo restituisce false se key è di tipo non assegnabile al tipo di chiave TKey del Dictionary<TKey,TValue>.This method returns false if key is of a type that is not assignable to the key type TKey of the Dictionary<TKey,TValue>.

Questo metodo si avvicina un'operazione o (1).This method approaches an O(1) operation.

Si applica a