Updated: September 2009
Defines methods to support the comparison of objects for equality.
Assembly: mscorlib (in mscorlib.dll)
This interface allows the implementation of customized equality comparison for collections. That is, you can create your own definition of equality for type T, and specify that this definition be used with a collection type that accepts the generic interface. In the .NET Framework, constructors of the Dictionary(TKey, TValue) generic collection type accept this interface.
This interface supports only equality comparisons. Customization of comparisons for sorting and ordering is provided by the IComparer(T) generic interface.
We recommend that you derive from the EqualityComparer(T) class instead of implementing the interface, because the EqualityComparer(T) class tests for equality using the IEquatable(T).Equals method instead of the Object.Equals method. This is consistent with the Contains, IndexOf, LastIndexOf, and Remove methods of the Dictionary(TKey, TValue) class and other generic collections.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.