• Article

IDictionary.Contains Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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

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

Syntax

'Declaration
Function Contains ( _
    key As Object _
) As Boolean

bool Contains(
    Object key
)

Parameters

Return Value

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

Exceptions

Exception Condition
ArgumentNullException

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

Remarks

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.

Examples

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

Silverlight

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

Platforms

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