From: Bob Hutchison <hutch@...>
Date: 2007-10-02T11:59:03+09:00
Subject: Re: instance variable/ I'm lost

Hi,

Welcome!

On 1-Oct-07, at 10:21 PM, Erik Boling wrote:

> Hello i am new to programming/ ruby but i have had some help from a
> cousin and read a book so i have some knowlage of what I'm doing.
> Anyways in my free time i was creating a program that tested me on  
> easy
> multiplication problems to keep my mind fresh;
>
> 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. Can't i  
> make
> a seperate def and create and instance variable like
> def correct
> @correct = correct
>
> then in my multiplication def. under the if statement do
> correct + 1
>
> then finally at the end do
> puts correct
>  and that would give me the total correct, but thats not working  
> for me?
> 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!

As you say, an instance variable would work, this is written as:  
@correct -- I've inserted these below (unless I edited this  
incorrectly, it should work).


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 then
     puts "good job"
     @correct = @correct + 1
   else
     puts "You fail!"
   end
end

problems.to_i.times do
   multiply
end

puts "correct: #{@correct}"


Now you'll be asking yourself: so what is the instance that this is a  
variable of? And: what's running this program? Good questions. You'll  
need to learn about classes, objects, and scopes to answer them.

There is an alternative technique using parameters and returned values:

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(correct)
   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 then
     puts "good job"
     correct = correct + 1
   else
     puts "You fail!"
   end
   return correct
end

correct = 0
problems.to_i.times do
   correct = multiply(correct)
end

puts "correct: #{correct}"


Another thing I should mention, since you are just starting out... it  
is best if you are *very* rigourous about your code from the very  
beginning. This includes things like formatting your code. Some  
habits are hard to un-learn, so don't form them :-)

Have fun!

Cheers,
Bob

> ps: sorry long post :(
> -- 
> Posted via http://www.ruby-forum.com/.
>

----
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