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

Definition

Ermittelt, ob das IDictionary ein Element mit dem angegebenen Schlüssel enthält.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);
abstract member System.Collections.IDictionary.Contains : obj -> bool
override this.System.Collections.IDictionary.Contains : obj -> bool
Function Contains (key As Object) As Boolean Implements IDictionary.Contains

Parameters

key
Object

Der Schlüssel, der in der IDictionary gesucht werden soll.The key to locate in the IDictionary.

Returns

Boolean

true, wenn die IDictionary ein Element mit dem angegebenen Schlüssel enthält; andernfalls false.true if the IDictionary contains an element with the specified key; otherwise, false.

Implements

Exceptions

key ist nullkey is null.

Examples

Im folgenden Codebeispiel wird gezeigt, wie Sie die IDictionary.Contains-Methode der System.Collections.IDictionary-Schnittstelle mit einem-Dictionary<TKey,TValue>verwenden.The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a Dictionary<TKey,TValue>. Das Beispiel zeigt, dass die-Methode false zurückgibt, wenn ein Schlüssel mit dem falschen Datentyp bereitgestellt wird.The example demonstrates that the method returns false if a key of the wrong data type is supplied.

Das Codebeispiel ist Teil eines größeren Beispiels, einschließlich der Ausgabe, die für die IDictionary.Add-Methode bereitgestellt wird.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.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

Remarks

Diese Methode gibt false zurück, wenn key einen Typ hat, der dem Schlüsseltyp TKey der Dictionary<TKey,TValue>nicht zugewiesen werden kann.This method returns false if key is of a type that is not assignable to the key type TKey of the Dictionary<TKey,TValue>.

Diese Methode nähert sich einem O (1)-Vorgang.This method approaches an O(1) operation.

Applies to