Question

I am working with Ruby scripting language. I have a snippet here. Just want to know what is happening inside that with in the loop. Here is my code

#!/usr/bin/ruby

presidents = ["Ford", "Carter", "Reagan", "Bush1", "Clinton", "Bush2"]

for ss in 0...presidents.length
  print ss, ": ", presidents[presidents.length - ss - 1], "\n";
end

I know that it is to print the array in reverse order, but my intention is to know what is happening in

"presidents[presidents.length - ss - 1]"

Please help me understanding this. I am really confused with this.

Answer 1

It means that, whoever wrote this code, he was still learning Ruby :-p. That’s more idiomatic and, I hope, self-explanatory:

presidents.reverse_each.with_index do |name, index|
  puts "#{index}: #{name}"
end

About presidents[presidents.length - ss - 1]: ss starts at 0, so length-0-1 = length-1 -> last element of presidents. On the last iteration of the loop you have length - (length-1) -1 = 0, so the first element of presidents is shown. A simple reverse, nothing fancy.