The implementation of the Equals method is intended to perform a test for equality with another object of type T, the same type as the current object. The Equals 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, IEquatable<T>.Equals 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:
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 Equals 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 Equals, you should also override the base class implementations of Object.Equals(Object) and GetHashCode so that their behavior is consistent with that of the IEquatable<T>.Equals 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. In addition, you should overload the op_Equality and op_Inequality operators. This ensures that all tests for equality return consistent results, which the example illustrates.