IEqualityComparer Interface

IEqualityComparer Interface


Defines methods to support the comparison of objects for equality.

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

type IEqualityComparer = interface end

System_CAPS_pubmethodEquals(Object, Object)

Determines whether the specified objects are equal.


Returns a hash code for the specified object.

This interface allows the implementation of customized equality comparison for collections. That is, you can create your own definition of equality, and specify that this definition be used with a collection type that accepts the IEqualityComparer interface. In the .NET Framework, constructors of the Hashtable, NameValueCollection, and OrderedDictionary collection types accept this interface.

This interface supports only equality comparisons. Customization of comparisons for sorting and ordering is provided by the IComparer interface.

For the generic version of this interface, see System.Collections.Generic.IEqualityComparer<'T>.

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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