IDictionary.Contains Method

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

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)


Function Contains ( _
    key As Object _
) As Boolean
bool Contains(
    Object key


Return Value

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


Exception Condition

key is nulla null reference (Nothing in Visual Basic).


Implementations can vary in whether they allow the key to be nulla null reference (Nothing in Visual Basic).

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.


The following code example demonstrates how to implement the Contains method. This code example is part of a larger example provided for the IDictionary class.

Public Function Contains(ByVal key As Object) As Boolean Implements IDictionary.Contains
   Dim index As Integer
   Return TryGetIndexOfKey(key, index)
End Function
public bool Contains(object key)
   Int32 index;
   return TryGetIndexOfKey(key, out index);

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.