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Collection<T>.Contains Method

Determines whether an element is in the Collection<T>.

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

public bool Contains(
	T item
)

Parameters

item
Type: T

The object to locate in the Collection<T>. The value can be null for reference types.

Return Value

Type: System.Boolean
true if item is found in the Collection<T>; otherwise, false.

Implements

ICollection<T>.Contains(T)

If the Collection<T> object is created using the default constructor, this method determines equality using the default equality comparer EqualityComparer<T>.Default for T, the type of values in the list. If type T does not implement the IEquatable<T> interface, the Equals method is used.

If the Collection object is created by passing an IList<T> object to the constructor, the Contains method will be determined by the IEqualityComparer<T> interface used by that IList<T> object.

This method performs a linear search; therefore, the average execution time is proportional to Count. That is, this method is an O(n) operation, where n is Count.

.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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