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IDictionary.Contains Method

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

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

bool Contains(
	Object key
)

Parameters

key
Type: System.Object

The key to locate in the IDictionary object.

Return Value

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

ExceptionCondition
ArgumentNullException

key is null.

Implementations can vary in whether they allow the key to be null.

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 bool Contains(object key)
{
   Int32 index;
   return TryGetIndexOfKey(key, out index);
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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