From: Alex Gutteridge <alexg@...>
Date: 2007-10-02T11:46:18+09:00
Subject: Re: instance variable/ I'm lost

On 2 Oct 2007, at 11:21, Erik Boling wrote:

> puts 'How many problems do you want to solve?'
> problems = gets.chomp
>
> 5.downto(1) do |x|
>   puts "The test will beging #{x} in seconds! "
>   sleep 1
> end
> puts 'Start!'
>
>   def multiply
> multiple2 = rand(11)
> multiple1 = rand(11S)
>   answer = multiple1 * multiple2
> puts 'what is ' + multiple1.to_s + ' * ' + multiple2.to_s + ' ?'
>   answerp = gets.chomp
>   if answer.to_s == answerp.to_s
>     puts "good job"
>   else puts "You fail!"
>   end
> end
>
> problems.to_i.times do multiply
> end
>
> :
> So i was wondering, how can i tally up how many times they answer
> correctly. I tried putting in the definition after the if statement
> correct + 1, * obviously i made the variable "correct" above* but the
> problem is, i cant retrive the variable out of the definition i had
> made. which brings me to my question of instance variables.

Instance variables are for (as you note below) classes. You don't  
have a class so you don't need to use instance variables.

The simplest solution here would be to use a global ($correct),  
though globals are usually frowned upon in larger programs:

puts 'How many problems do you want to solve?'
problems = gets.chomp

$correct = 0

5.downto(1) do |x|
   puts "The test will beging #{x} in seconds! "
   sleep 1
end
puts 'Start!'

def multiply
   multiple2 = rand(11)
   multiple1 = rand(11)
   answer = multiple1 * multiple2
   puts 'what is ' + multiple1.to_s + ' * ' + multiple2.to_s + ' ?'
   answerp = gets.chomp
   if answer.to_s == answerp.to_s
     puts "good job"
     $correct += 1
   else puts "You fail!"
   end
end

problems.to_i.times do multiply
end

puts "You scored #{$correct}/#{problems}"

> i dont know what im doing wrong? I see these instance variable in this
> confusing book i just started to read, and it looks like maybe there
> needs to be a class?!?!? idk but if someone could help me get this  
> stuff
> figured out that would be awesome!
> ps: sorry long post :(

I don't know what confusing book you are reading, but their are many  
excellent tutorials for Ruby which will explain these concepts better  
than I can. See any of the recent 'I'm a beginner what book should I  
read?' threads.

Alex Gutteridge

Bioinformatics Center
Kyoto University