However, this is an implementation detail and unless you want to rely on this in your code you cannot create a stable hash code provide an object that implements IStructuralEquatable.

= to provide value equality checks (vs the default reference equality check). The MSDN documentation suggests you only do it for immutable types. There are also issues involving interfaces and operator overloading.

Reference types (read classes) don't benefit as much. The IEquatable implementation does let you avoid a cast from System.Object but that's a very trivial gain. I still like IEquatable to be implemented for my classes since it logically makes the intent explicit.

Daniel A.A. PelsmaekerDaniel A.A. Pelsmaeker 49.2k2121 gold badges112112 silver badges160160 bronze badges 5 In addition to answers which point to duplicate hashcodes bey is documented behavior, some reasoning and reflection would also lead you to the same conclusion.

Although I think the gains from not boxing will be less than the cost for having CanEqual. In that case you should seal your types and you no longer need CanEqual. Sealing also saf some performance benefits.

– Royi Namir Commented Mar 3, 2012 at 18:04 @RoyiNamir user844541's answer is correct, but maybe it is still hard for you to understand without a concrete example, if you are familiar with IEqualityComparer and how it is used by Linq's Distinct(), then after check the source code to see how it implement IStructuralEquatable on referencesource.microsoft.com/#mscorlib/system/collections/…, then you will see how it work.

1 My understanding is that it's used for collection like types, and encapsulates the structural part of the comparison, but leaved the comparison of the elements to a comparer passed in by the user. But I'm not really sure if I really got it.

In my implementation I delegated the task of calculating hash codes to the internal array. While testing it, to my great C# IStructuralEquatable Kullanımı surprise, I found that my two different arrays had the same structural hash code

comparer IEqualityComparer İki nesnenin tay olup olmadığını gitmek ciğerin kullanılacak yöntemi tanılamamlayan nesne.

In addition to this awesome blog Frank and I also dicussed all of this awesome in detail on Merge Conflict on episode 111:

Each of your objects should use a hashcode based on the contents of the object. If you have a value type containing 3 ints, use those when computing the hash code. Like this, all objects with identical content will have the same hash code, independent of app domain and other circumstances.

IStructuralEquatable is used with arrays to determine whether the arrays are structurally equal. The StructuralEqualityComparer.Equals method is used for this purpose.

Here the comparison is different for value type arrays and custom arrays. In .Safi 4.0 int, string will internally implement IEquatable for custom types we have to externally implement the IEquatable.

Burada dikkat ederseniz eğer ms.x ve ms.y bileğaksiyonmeyeceğinden dolayı bir Deep Copy hanek konusudur. Eğer referans tipli strüktürlar olsalardı dundaki kabilinden bir sonuç elde edilecekti ve Shallow Copy kelam konusu olacaktı.