Definitive Guide C# IEqualityComparer nerelerde kullanılıyor için

Definitive Guide C# IEqualityComparer nerelerde kullanılıyor için

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Provides an equality check when there is only one way of comparing the objects (implemented inside the class)

This transformation allows for faster comparison of elements during look-up, because the elements of the second takım are easier to compare and because there are fewer of them. Still, due to this same reason any hash function might eventually produce equal codes for non equal objects

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ArgumentException özelliği bir bileğere ayarlanır, fakat karma tablosu ve kullanılarak IHashCodeProviderICompareroluşturulmuştur.

Therefore, when testing two instances of T for equality, because T özgü no internal understanding of equality, you will have to make an explicit choice of a IEqualityComparer instance which performs the sınav according to your specific requirements.

It is essentially the same for this purpose with one subtle difference. In your first example you override Equals using a parameter of type Object and then have to cast it to Customer, however, in your second example you are able to have the parameter of type Customer which means there is no need to cast.

BaseClass satisfies the first bound because it is larger than the first bound, and identical to the second bound.

More importantly, I C# IEqualityComparer nedir have stepped into the trap of thinking that objects, which I use in my code, hayat be only partially relevant to me, while in case we do OOP every object must be considered in its entirety (things like SOLID help us with that.) This way, when implementing the IEqualityComparer interface I should have paid more attention to the presence of GetHashCode(..) method. This would solve my mesele at once, because it is this same method that LINQ uses when asked to extract distinct objects and perform other equality related operations (see C# IEqualityComparer nedir Seki operators in this article). To verify this we add a debug message to the method and observe several calls to it:

Derslik tanılamamlama, kodun yine kullanılabilirliğini pozitifrır, hizmetı kolaylaştırır ve kodun okunabilirliğini geliştirir.

When we make the inference from the comparer we say "IEqualityComparer is contravariant in T, so we birey C# IEqualityComparer Kullanımı accept BaseClass or any smaller type

One feature I wish C# IEqualityComparer nedir .Safi had which would improve the usefulness of such dictionaries would be a means of requesting the actual key object associated with a given key (so if the dictionary contained the string "WowZo" bey a key, one could look up "wowzo" and C# IEqualityComparer Nasıl Kullanılır get "WowZo"; unfortunately, the only way to retrieve an actual key object, if TValue doesn't contain a redundant reference to it, is to enumerate the entire collection).

Finally, if you just need to filter collection for distinct values based on some key and you want to do it quickly with kakım few additional actions kakım possible, there is a trick that doesn't require creating new types:

The result is the same bey when using the first version of ActorComparer, although the new one is much more flexible in the sense that it may be used differently in different contexts and no further modifications are required to its code.