Converts a Gzipped text file into a csv. Text file has a specific structure. And this is exactly how not to code in Ruby

worst_implementation_statement.rb

require 'zlib'

file = *ARGV
file.each do |eachfile| 
  Zlib::GzipReader.open(eachfile) do |f|
    account = ""
    result = []
    f.each_line do |line|
      next unless line[/\d{17}/]
      account = line[6,11]
      a = {
        :date_one => line[17, 8],
        :date_two => line[25, 8],
        :narration => line[33, 150].strip,
        :transaction_crdr => line[183],
        :tr_amount => line[184, 16].to_i/100.00,
        :total_amt => line[200],
        :total_balance => line[201, 16].to_i/100.00
      }
      b = a.collect {|k,v| "#{v}"}
      result << b.join(',')
    end
    File.open("#{account}_output.csv", "w") do |f|
      f << result.join("\n")
    end
  end
end