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IDictionary.Contains Method

SortedList(Of TKey, TValue).IDictionary.Contains Method

Determines whether the IDictionary contains an element with the specified key.

Namespace:  System.Collections.Generic
Assemblies:   System (in System.dll)
  System.Collections (in System.Collections.dll)

Private Function Contains ( _
	key As Object _
) As Boolean Implements IDictionary.Contains


Type: System.Object

The key to locate in the IDictionary.

Return Value

Type: System.Boolean
true if the IDictionary contains an element with the key; otherwise, false.




key is Nothing.

This method returns false if key is of a type that is not assignable to the key type TKey of the SortedList(Of TKey, TValue).

This method is an O(log n) operation, where n is Count.

The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a SortedList(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 sorted list of strings, with string keys, 
        ' and access it using the IDictionary interface. 
        Dim openWith As IDictionary = _
            New sortedList(Of String, String)

        ' Add some elements to the sorted list. 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}", _
End If 

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


    End Sub 

End Class

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
© 2015 Microsoft