EqualityComparer(T) Class
Provides a base class for implementations of the IEqualityComparer(T) generic interface.
Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)
The EqualityComparer(T) type exposes the following members.
.gif?cs-save-lang=1&cs-lang=fsharp "Public property")
.gif?cs-save-lang=1&cs-lang=fsharp "Static member")
| Name | Description | |
|---|---|---|
.gif?cs-save-lang=1&cs-lang=fsharp "Public method") .gif?cs-save-lang=1&cs-lang=fsharp "Supported by the XNA Framework") .png?cs-save-lang=1&cs-lang=fsharp "Supported by Portable Class Library") .png?cs-save-lang=1&cs-lang=fsharp "Supported in .NET for Windows Store apps") | Equals(Object) | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
| Equals(T, T) | When overridden in a derived class, determines whether two objects of type T are equal. |
.gif?cs-save-lang=1&cs-lang=fsharp "Protected method") | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode() | Serves as a hash function for a particular type. (Inherited from Object.) |
| GetHashCode(T) | When overridden in a derived class, serves as a hash function for the specified object for hashing algorithms and data structures, such as a hash table. |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| ToString | Returns a string that represents the current object. (Inherited from Object.) |
| Name | Description | |
|---|---|---|
.gif?cs-save-lang=1&cs-lang=fsharp "Explicit interface implemetation") .gif?cs-save-lang=1&cs-lang=fsharp "Private method") | IEqualityComparer.Equals | Determines whether the specified objects are equal. |
| IEqualityComparer.GetHashCode | Returns a hash code for the specified object. |
Derive from this class to provide a custom implementation of the IEqualityComparer(T) generic interface for use with collection classes such as the Dictionary(TKey, TValue) generic class, or with methods such as List(T).Sort.
The Default property checks whether type T implements the System.IEquatable(T) generic interface and, if so, returns an EqualityComparer(T) that contains the implantation of the IEquatable(T).Equals method. Otherwise, it returns an EqualityComparer(T), as provided by T.
We recommend that you derive from the EqualityComparer(T) class instead of implementing the IEqualityComparer(T) 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.
The following example creates a dictionary collection of objects of type Box with an equality comparer. Two boxes are considered equal if their dimensions are the same. It then adds the boxes to the collection.
The dictionary is recreated with an equality comparer that defines equality in a different way: Two boxes are considered equal if their volumes are the same.
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.
