CODEWITHSUNDEEP
ruby
Ajedi32
Ajedi32

Reputation: 48338

Why does Ruby's Fixnum#/ method round down when it is called on another Fixnum?

Okay, so what's up with this?

irb(main):001:0> 4/3
=> 1
irb(main):002:0> 7/8
=> 0
irb(main):003:0> 5/2
=> 2

I realize Ruby is doing integer division here, but why? With a langauge as flexible as Ruby, why couldn't 5/2 return the actual, mathematical result of 5/2? Is there some common use for integer division that I'm missing? It seems to me that making 7/8 return 0 would cause more confusion than any good that might come from it is worth. Is there any real reason why Ruby does this?

Upvotes: 3

Views: 492

Answers (1)

Eureka
Eureka

Reputation: 6145

Because most languages (even advanced/high-level ones) in creation do it? You will have the same behaviour on integer in C, C++, Java, Perl, Python... This is Euclidian Division (hence the corresponding modulo % operator).

The integer division operation is even implemented at hardware level on many architecture. Others have asked this question, and one reason is symetry: In static typed languages such as see, this allows all integer operations to return integers, without loss of precision. It also allow easy access to the corresponding low-level assembler operation, since C was designed as a sort of extension layer over it.

Moreover, as explained in one comment to the linked article, floating point operations were costly (or not supported on all architectures) for many years, and not required for processes such as splitting a dataset in fixed lots.

Upvotes: 5

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