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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>

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, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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