From: Jose Augusto <jasaugusto@...>
Date: 2006-12-27T11:51:47+09:00
Subject: Re: Peculiar Behavior for a Newby to Undertstand

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Hi Charles,

I entered the code in Ruby 1.8.5 in Windows, using Scintilla IDE :-))
(the joke is that Scintilla-Scite is not an IDE at all!) it gave the error:

>ruby prime.rb
prime.rb:34: undefined local variable or method `primes' for main:Object
(NameError)

Then changed

a=primes.new
a.show_primes(1000000,1000100)

to

a=Primes::new
a.show_primes(1000000,1000100)

The good result appeared :-)

>ruby prime.rb
1000003 1000033 1000037 1000039 1000081 1000099 >Exit code: 0

Don't know how you had not an error instead of the wrong result before...
For that you need a Ruby guru :-)

Kind Regards

J. Augusto



On 12/27/06, Charles A Gray <smgspices@aol.com> wrote:
>
> I created a class for prime numbers as so:
>
> class Primes
>     def initialize
>     end
>
>     def prime?(number)
>         # Method returns true if number is prime.
>         limit = Math.sqrt(number).ceil
>         flag = true
>         if number % 2 == 0
>             flag = false
>         else
>             3.step(limit,2) {|i|
>                 if number % i == 0
>                     flag = false
>                     break
>                 end
>             }
>         end
>         return flag
>     end
>
>     def show_primes(lower, upper)
>         # Prints all primes between lower and upper
>         # Lower is incremented 1 if it is even.
>         # The arcane "(((lower/2).floor)*2+1)" performs this task
>         (((lower/2).floor)*2+1).step(upper,2) {|i|
>             if prime?(i) == true
>                 print i.to_s + " "
>             end
>         }
>     end
>     end
> Then when I enter
> a=primes.new
> a.show_primes(1000000,1000100) I get
> 1000003 1000033 1000037 1000039 1000081 1000099 1000001
> Where is that trailing 1000001 coming from? It is not a prime number and
> in fact is the lower limit.
> If I enter the same methods outside of class Primes and enter
> show_primes(1000000,1000100) I don't get the lower limit at the end of
> the printed values.
>
> I am running version 1.18.4 using scite in Ubuntu.
> --
> Charles Gray -- Phoenix, AZ; Where you can bake the chill out of your
> bones
>
>
>
>

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