Updated: July 2008
Indicates whether the current object is equal to another object of the same type.
Assembly: mscorlib (in mscorlib.dll)
The implementation of the method is intended to perform a test for equality with another object of type T, the same type as the current object. The method is called in the following circumstances:
When the Equals method is called and the other parameter represents a strongly-typed object of type T. (If other is of type Object, the base Object.Equals(Object) method is called. Of the two methods, offers slightly better performance.)
When the search methods of a number of generic collection objects are called. Some of these types and their methods include the following:
Some of the generic overloads of the BinarySearch method.
In other words, to handle the possibility that objects of a class will be stored in an array or a generic collection object, it is a good idea to implement IEquatable(T) so that the object can be easily identified and manipulated.
When implementing the method, define equality appropriately for the type specified by the generic type argument. For example, if the type argument is Int32, define equality appropriately for the comparison of two 32-bit signed integers.Notes to Implementers:
If you implement , you should also override the base class implementations of Object.Equals(Object) and GetHashCode so that their behavior is consistent with that of the method. If you do override Object.Equals(Object), your overridden implementation is also called in calls to the static Equals(System.Object, System.Object) method on your class. This ensures that all invocations of the Equals method return consistent results, which the example illustrates.
The following example shows the partial implementation of a Person class that implements IEquatable(T) and has two properties, LastName and SSN. The method returns True if the SSN property of two Person objects is identical; otherwise, it returns False.
Person objects can then be stored in a List(T) object and can be identified by the Contains method, as the following example shows.
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.