From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2011-01-04T04:00:28+09:00
Subject: Re: Different behaviour in irb and ruby

On Mon, Jan 3, 2011 at 7:38 PM, Vincent V. <vvanmulders@gmail.com> wrote:
> I'm new to Ruby and just finished my first program.
>
> # simple quiz program
> questions={"Question 1"=>"Answer 1",
>           "Question 2"=>"Answer 2",
>           "Question 3"=>"Answer 3",
>           "Question 4"=>"Answer 4",
>           "Question 5"=>"Answer 5",
>           "Question 6"=>"Answer 6",
>           "Question 7"=>"Answer 7",
>           "Question 8"=>"Answer 8",
>           "Question 9"=>"Answer 9",
>           "Question 10"=>"Answer 10"}
> score=0
> i=0
> while i<10
>  puts questions.keys[i]
>  if gets.chomp == questions.values[i]
>    puts "Good answer !"
>    score+=1
>  else
>    puts "Bad answer !"
>  end
>  i+=1
> end
>
> puts "Your score is #{score}/10."
>
> When I past it in irb(0.9.5) it just runs fine, but when it runs with
> ruby(1.8.7) or (1.9.2) the order of the questions changes.
>
> Can someone explain me what goes wrong (and why)?

If you want to access the answers by question number, you should use
an array and not a Hash. In Ruby 1.9 the Hash maintains the keys in
insertion order, but this is not the case in Ruby 1.8, I think. I'm
not sure why you find that behaviour in 1.9.2. In any case, I think
you should use an Array.

Jesus.