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EqualityComparer(T).Default Property

Returns a default equality comparer for the type specified by the generic argument.

Namespace:  System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)
static member Default : EqualityComparer<'T> with get

Property Value

Type: System.Collections.Generic.EqualityComparer(T)
The default instance of the EqualityComparer(T) class for type T.

The Default property checks whether type T implements the System.IEquatable(T) interface and, if so, returns an EqualityComparer(T) that uses that implementation. Otherwise, it returns an EqualityComparer(T) that uses the overrides of Object.Equals and Object.GetHashCode provided by T.

The following example creates two dictionary collections of type Box. Both dictionaries are created with the constructor that takes an EqualityComparer(T) as a parameter.

To determine the equality of dictionary keys, the boxesByDim dictionary uses an equality comparer (BoxEqDimensions) that uses the implementation of the IEquatable(T).Equals method in the Box class. Two boxes are considered equal if their dimensions are the same.

The boxesByVol dictionary uses an equality comparer (BoxEqVolume) that defines equality by volume. Two boxes are considered equal if their volumes are the same.

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

.NET Framework

Supported in: 4.5.1, 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

.NET for Windows Phone apps

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

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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