[SOLVED] more weird ruby arithmetic

bigearsbilly · 03-27-2015, 05:21 AM

More unexpected results for ruby arithmetic.
Standard integer arithmetic (not float)

Code:

irb(main):001:0> 1 / 5
=> 0

OK that is cool, what I expected, nice, I can dig it.
then...

Code:

irb(main):002:0> -1 / 5
=> -1

Wtf?

Is it me or has the world gone mad?

it gets worse!

Code:

irb(main):004:0> -7/5
=> -2

irb(main):005:0> -30/5
=> -6
irb(main):006:0> -31/5
=> -7

I mean, really!?

a4z · 03-27-2015, 06:16 AM

and in python it's the same, I mean, really!
here are the reasons
http://python-history.blogspot.de/20...on-floors.html

possible perl an option for you?

NevemTeve · 03-27-2015, 06:29 AM

@OP: Exactly what is your problem/question?

bigearsbilly · 03-27-2015, 06:34 AM

aah interesting article.

well, i generally use C and Perl but I like to use the ruby interactive interpreter for arithmetic and testing little functions. I am adjusting a C function and I use the irb to quickly mess about with it.

Strangely the ruby version worked for precisely those reasons.
I hate surprises.

edit:
thanks a lot I have solved my problem by implementing the floored division.

bigearsbilly · 03-27-2015, 06:48 AM

Quote:

Originally Posted by NevemTeve

@OP: Exactly what is your problem/question?

not sure, some days the old brain doesn't quite work properly.

a4z · 03-27-2015, 08:32 AM

Quote:

Originally Posted by bigearsbilly

thanks a lot I have solved my problem by implementing the floored division.

implemented? it is already implemented

Code:

irb(main):017:0> -1.0/5
=> -0.2
irb(main):018:0> -1/5.0
=> -0.2
irb(main):019:0> -1/5.to_f
=> -0.2
irb(main):021:0> -1/5.to_f
=> -0.2
irb(main):022:0> -1.to_f/5.to_f