C# IEqualityComparer Kullanımı Herkes İçin Eğlenceli Olabilir

C# IEqualityComparer Kullanımı Herkes İçin Eğlenceli Olabilir

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The last statement basically means that in case we rely on Equals(..) method we could calculate hash based only on the last name and the result will still be the same:

When testing two instances for equality you have to make an explicit choice of which IEqualityComparer instance to use.

Enum’ı muhakkak yazdığımız projelerde kullanmışızdır. Done ayaında bazı alanları öngörebiliriz.Bu alanlar belli bir fehamet kümesine sahiptir. Bunları done analizindeki kategorik verilere benzetebiliriz ve alanların alabileceği değerler önceden belirlidir, sabittir ve rahatletilebilir. Bu gidiş enum ile elan okunabilir kod yazmamızı ve bu numerik değerlerin ne kavrama geldiğini anlamamızı olanak katkısızlar.

CodeFuller's answer will work fine, but as an alternative option, you could use MoreLINQ and its DistinctBy method, which would avoid you needing to create a separate class at all:

IEqualityComparer is an interface for an object that performs the comparison on two objects of the type T.

If you change your class to implement IEquatable instead, the implementation of Distinct (which will use EqualityComparer.Default which in turn sees your type implements IEquatable and delegates to that) will work kakım you expect.

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.

We’ll write a classic implementation of IEqualityComparer C# IEqualityComparer Temel Özellikleri ve Kullanımı class. In our example, we need to compare customers. Two customers are distinct if your first char Name is different.

For me it seemed that LINQ simply ignored my equality comparer and kept doing everything on its own. In fact, we could check this by adding a debug output to Equals method:

If we call a Distinct LinQ Extension Method, the result would be a new sequence with 7 elements, and we would not find any distinct member.

I think the other post you mention is C# IEqualityComparer Nasıl Kullanılır saying that EqualityComparer implements IEqualityComparer and IEqualityComparer, so you don't have to implement both the generic and non-generic interfaces if you derive from EqualityComparer.

So there you go. In this situation, type inference chooses the more general type and infers that the call C# IEqualityComparer Nasıl Kullanılır means Distinct. Type inference never takes the return type

carlosfigueiracarlosfigueira 56533 silver badges66 bronze badges $endgroup$ 5 $begingroup$ one question I have for you @carlosfigueira is in regards to your suggestion to handle dictionaries: How would you know the part of the IEnumerable you are checking against?

Or if you need to change how the comparer sorts, that you have C# IEqualityComparer Kullanımı to change them all? Lets say you do that comparison in 500 places, some in 3rd party C# IEqualityComparer nedir code, now you have a maintenance nightmare.