C# IStructuralEquatable nerelerde kullanılıyor Herkes İçin Eğlenceli Olabilir

Wiki Article

If two objects compare as equal, the GetHashCode method for each object must return the same value. However, if two objects do derece compare as equal, the GetHashCode methods for the two object do derece have to return different values.

In certain scenarios (such kakım using the value type birli a key in a dictionary) it sevimli murder performance in one foul swoop.

Reference types (read classes) don't benefit birli 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.

You generic method katışıksız a type parameter T but the type is not part of the signature of the function so how is T supposed to be used in the function? Anyway, you dirilik use .Kupkuru tuples or anonymous types to create hash codes by combining values but I am hamiş sure this answers your question.

Your browser isn’t supported anymore. Update it to get the best YouTube experience and our latest features. Learn more

The IEquatable implementation will require one less cast for these classes and birli a result will be slightly faster than the standard object.Equals method that would be used otherwise. As an example see the different implementation of the two methods:

I've noticed these two interfaces, and several associated classes, have been added in .NET 4. They seem a bit superfluous to me; I've read several blogs about them, but I still birey't figure out what sorun they solve that was tricky before .Safi C# IStructuralEquatable Nasıl kullanılır 4.

Reading through the excellent blog post by Sergey on struct equality performance he mentions that the default implementations are pretty slow and using boxing for each member. Additionally, he mentions that a memory comparison may not give you the correct results in this super simple example:

Collaborate with us on GitHub The source for this content yaşama be found on GitHub, where you gönül also create and review issues and pull requests. For more information, see our contributor guide.

C# IStructuralComparable Determines whether the current collection object precedes, occurs in the same position bey, or follows another object in the sort order.

The example on MSDN gives part of the answer here; it seems to be useful for heterogeneous equality, rather than homogeneous equality - i.e. for testing whether two objects (/values) of potentially different types

Just look at the default ValueType.Equals(object) code that gets called otherwise. It's an absolute performance killer that introduces boxing, type evaluation and finally falls back on reflection if any of the fields are reference types.

While writing my own immutable ByteArray class that uses a byte array internally, I implemented the IStructuralEquatable interface.