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Dictionary(Of TKey, TValue).IDictionary.Contains Method (Object)
.NET Framework (current version)
Determines whether the IDictionary contains an element with the specified key.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- key
-
Type:
System.Object
The key to locate in the IDictionary.
Return Value
Type: System.Booleantrue if the IDictionary contains an element with the specified key; otherwise, false.
Implements
IDictionary.Contains(Object)| Exception | Condition |
|---|---|
| ArgumentNullException | key is null. |
This method returns false if key is of a type that is not assignable to the key type TKey of the Dictionary(Of TKey, TValue).
This method approaches an O(1) operation.
The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a Dictionary(Of TKey, TValue). The example demonstrates that the method returns false if a key of the wrong data type is supplied.
The code example is part of a larger example, including output, provided for the IDictionary.Add method.
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 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))
Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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