Ruby Noob issue

ruby-talk
1

Hi
I'm really new to Ruby
as such it took me about an hour to register ^^'...
That being said

I am trying to figure out why this program I made keeps returning as "0"

def f(x)
return (5/9) * (x-32)
end
x=1001
print(f(x))

Not complicated at all
I'm just intending for the x value 1001 to plug its self into the
temperature equation and print that value

Thanks for reading

···

--
Posted via http://www.ruby-forum.com/.

2

Fred, (5/9) is integer division. The decimal part is truncated leaving you
with 0. Use (5.0/9) instead.
Satish

···

On Fri, Sep 25, 2009 at 6:37 AM, Fred Ige <duelarm@gmail.com> wrote:

Hi
I'm really new to Ruby
as such it took me about an hour to register ^^'...
That being said

I am trying to figure out why this program I made keeps returning as "0"

def f(x)
return (5/9) * (x-32)
end
x=1001
print(f(x))

Not complicated at all
I'm just intending for the x value 1001 to plug its self into the
temperature equation and print that value

Thanks for reading
--
Posted via http://www.ruby-forum.com/\.

3

Satish Talim wrote:

Fred, (5/9) is integer division. The decimal part is truncated leaving
you
with 0. Use (5.0/9) instead.
Satish

Thanks! It works now
I cant believe such a small issue throw me off for so long.

···

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Posted via http://www.ruby-forum.com/\.

4

Welcome to Ruby, Fred!

···

On 09/25/2009 03:17 AM, Fred Ige wrote:

Satish Talim wrote:

Fred, (5/9) is integer division. The decimal part is truncated leaving you
with 0. Use (5.0/9) instead.
Satish

Thanks! It works now
I cant believe such a small issue throw me off for so long.

Well, the good news is that you learned it early the hard way and won't forget it anytime soon. That will help you avoid such errors in more complex code where they are more difficult to spot. :slight_smile:

Kind regards

  robert

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

5

Was it more than two days?

If not, I think you're ahead of the curve. The real question is how long
it will take you to figure out why some similar expression is coming out
0 in three or four years. :slight_smile:

-s

···

On 2009-09-25, Fred Ige <duelarm@gmail.com> wrote:

Thanks! It works now
I cant believe such a small issue throw me off for so long.

--
Copyright 2009, all wrongs reversed. Peter Seebach / usenet-nospam@seebs.net
| Seebs.Net <-- lawsuits, religion, and funny pictures
Fair game (Scientology) - Wikipedia <-- get educated!

6

Hi,

Satish Talim wrote:
> Fred, (5/9) is integer division. The decimal part is truncated leaving
> you
> with 0. Use (5.0/9) instead.
> Satish

Thanks! It works now
I cant believe such a small issue throw me off for so long.

Actually, you're not the first one to stumble over the
integer/floating point problem.

As expressions are evaluated from left to right, the first number
coerces the value to be Float. You could also say:

  (x.to_f - 32) * 5 / 9

Or

  class Numeric
    def f2c
      (to_f - 32) * 5 / 9
    end
  end

  -32.f2c #=> 0.0

Here's another pitfall about floating point values. Be aware that
aren't exact in general.

  "%20.18f" % 0.3 #=> "0.299999999999999989"

Bertram

···

Am Freitag, 25. Sep 2009, 10:17:53 +0900 schrieb Fred Ige:

--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de