Can I build an array using a loop in Ruby?

Question

I just started learning Ruby/Rails, and am trying to write a program that builds an array, then formats the new array.

It works up to the second while, and, if I have an array already built, the second part works as well. Is there something I am leaving out?

chap = []
page = []
lineWidth = 80
x = 0
n = chap.length.to_i
puts 'chapter?'
chapter = gets.chomp
while chapter != ''
  chap.push chapter
  puts 'page?'
  pg = gets.chomp
  page.push pg
  puts 'chapter?'
  chapter = gets.chomp
end
puts ('Table of Contents').center lineWidth
puts ''
while x < n
 puts ('Chapter ' + (x+1).to_s + ' ' + chap[x]).ljust(lineWidth/2) +(' page ' + page[x]).rjust(lineWidth/2)
 x = x + 1
end

Thanks for your help!

the length n is calculated before actually building the chap array, therefore x == n == 0. Move n=chap.length.to_i to after the first while. Also you don't need to_i — mastaBlasta
– mastaBlasta, Commented Sep 24, 2013 at 17:51
As a note on style, chapter != '' is not very pretty. Better is something like !chapter.empty? where you're testing chapter itself, not doing a comparison against another string. x += 1 is also preferable to x = x + 1. — tadman
– tadman, Commented Sep 24, 2013 at 18:48

Buzz Moschetti · Accepted Answer · 2013-09-24 17:54:15Z

3

Simple pilot error: You called

n = chap.length.to_i

too early. You have to get the length of the chap list AFTER you put things in it. Move that line here:

    ...
    puts 'chapter?'
    chapter = gets.chomp
end
n = chap.length.to_i

puts ('Table of Contents').center lineWidth

and it works fine.

answered Sep 24, 2013 at 17:54

Buzz Moschetti

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