CODEWITHSUNDEEP
c#castingcomparison
colinfang
colinfang

Reputation: 21767

Is it true that comparison is slower than type casting, and boxing is even slower?

I heard about that type casting is slow. I had thought comparison is fast, but...

It seems IComparable.CompareTo(object y) has to use the cast, which would make x > y at least as slow as y as MyClass if not slower if there is no IComparable<T> available.

So, am I right to say that:

It is always better to implement IComparable<T> than IComparable because then we don't have to type cast?

Update

Is boxing much slower than type casting between 2 reference types?

Upvotes: 0

Views: 178

Answers (2)

Jon
Jon

Reputation: 437734

From a performance standpoint it's always better to implement the generic versions of these interfaces because it's a guarantee that you will avoid the boxing of value types, which is the #1 performance killer in this type of scenario.

It is also the case that the generic versions will also not need to make runtime type checks, but the performance hit from these checks is very smaller than that from boxing and will be much harder to notice in practice.

Seeing as there's nothing you lose by implementing IComparable<T> then the conclusion it's clear: you should always do it, as there's nothing to lose and potentially quite a bit to gain.

Upvotes: 1

Oscar
Oscar

Reputation: 13990

It's always better implement generics. Not only for performance, also because you get compile time checking.

Upvotes: 0

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