.NET Framework Class Library
CollectionTContains Method

Determines whether an element is in the CollectionT.

Namespace:   System.Collections.ObjectModel
Assembly:  mscorlib (in mscorlib.dll)
Public Function Contains ( _
	item As T _
) As [%$TOPIC/ms132407_en-us_VS_110_2_0_0_0_0%]
public [%$TOPIC/ms132407_en-us_VS_110_2_0_1_0_0%] Contains(
	T item
virtual [%$TOPIC/ms132407_en-us_VS_110_2_0_2_0_0%] Contains(
	T item
) sealed
abstract Contains : 
        item:'T -> [%$TOPIC/ms132407_en-us_VS_110_2_0_3_0_0%]  
override Contains : 
        item:'T -> [%$TOPIC/ms132407_en-us_VS_110_2_0_3_0_1%]
public final function Contains(
	item : T
) : [%$TOPIC/ms132407_en-us_VS_110_2_0_4_0_0%]


Type: T

The object to locate in the CollectionT. The value can be for reference types.

Return Value

Type: SystemBoolean
true if item is found in the CollectionT; otherwise, false.



If the CollectionT object is created using the default constructor, this method determines equality using the default equality comparer EqualityComparerTDefault for T, the type of values in the list. If type T does not implement the IEquatableT interface, the Equals method is used.

If the Collection object is created by passing an IListT object to the constructor, the Contains method will be determined by the IEqualityComparerT interface used by that IListT 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.

Version Information

.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

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

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

Portable Class Library

Supported in: Portable Class Library