CollectionContains Method

Determines whether an element is in the Collection.

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

public bool Contains(
	T item
virtual bool Contains(
	T item
) sealed
abstract Contains : 
        item:'T -> bool
override Contains : 
        item:'T -> bool
Public Function Contains (
	item As T
) As Boolean


Type: T

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

Return Value


true if item is found in the Collection; otherwise, false.


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

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

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

Version Information
Universal Windows Platform
Available since 4.5
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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