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List(T).Contains Method

Determines whether an element is in the List(T).

Namespace:  System.Collections.Generic
Assemblies:   mscorlib (in mscorlib.dll)
  System.Collections (in System.Collections.dll)

abstract Contains : 
        item:'T -> bool  
override Contains : 
        item:'T -> bool


Type: T

The object to locate in the List(T). The value can be a null reference (Nothing in Visual Basic) for reference types.

Return Value

Type: System.Boolean
true if item is found in the List(T); otherwise, false.



This method determines equality by using the default equality comparer, as defined by the object's implementation of the IEquatable(T).Equals method for T (the type of values in the list).

This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

The following example demonstrates the Contains and Existsmethods on a List(T) that contains a simple business object that implements Equals.

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

The following example contains a list of complex objects of type Box. The Box class implements the IEquatable(T).Equals method so that two boxes are considered equal if their dimensions are the same. In this example, the Contains method returns true, because a box that has the specified dimensions is already in the collection.

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.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

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

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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