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Enumerable::Contains<TSource> Method (IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)

Updated: October 2008

Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

[ExtensionAttribute]
public:
generic<typename TSource>
static bool Contains(
	IEnumerable<TSource>^ source, 
	TSource value, 
	IEqualityComparer<TSource>^ comparer
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic::IEnumerable<TSource>

A sequence in which to locate a value.

value
Type: TSource

The value to locate in the sequence.

comparer
Type: System.Collections.Generic::IEqualityComparer<TSource>

An equality comparer to compare values.

Return Value

Type: System::Boolean
true if the source sequence contains an element that has the specified value; otherwise, false.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source is nullptr.

Enumeration is terminated as soon as a matching element is found.

If comparer is nullptr, the default equality comparer, Default, is used to compare elements to the specified value.

The following example shows how to implement an equality comparer that can be used in the Contains method.

No code example is currently available or this language may not be supported.

After you implement this comparer, you can use a sequence of Product objects in the Contains method, as shown in the following example.

No code example is currently available or this language may not be supported.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0

Date

History

Reason

October 2008

Added an example.

Customer feedback.

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