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Queryable.Contains<TSource> Method (IQueryable<TSource>, TSource, IEqualityComparer<TSource>)

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

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

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Contains(Of TSource) ( _
    source As IQueryable(Of TSource), _
    item As TSource, _
    comparer As IEqualityComparer(Of TSource) _
) As Boolean

public static bool Contains<TSource>(
    this IQueryable<TSource> source,
    TSource item,
    IEqualityComparer<TSource> comparer
)

Type Parameters

  • TSource
    The type of the elements of source.

Parameters

  • item
    Type: TSource
    The object to locate in the sequence.

Return Value

Type: System.Boolean
true if the input 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 IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter.

Exceptions

Exception Condition
ArgumentNullException

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

Remarks

The Contains<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Contains<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Contains<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) depends on the implementation of the type of the source parameter. The expected behavior is that it determines if source contains item by using comparer to compare values.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

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