Contains Method

Collection<T>.Contains Method (T)


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

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

public bool Contains(
	T 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.

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.

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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