Ruby：跳过获取值

所以我的问题是：为什么Ruby会跳过gets命令.

class Product
  attr_reader :id,:name,:price,:stock
  def initialize(id,name,price,stock)
    @id = id
    @name=name
    @price=price
    @stock=stock
  end
  def readout
    self.each do |product|
      print product.id
      print "|"
      print product.name
      print "|"
      print product.price
      print "|"
      print product.stock
      puts ""
    end
  end
end

products = []
newproducts= []

if ARGV[0] != nil
  if File.exist?(ARGV[0])
    File.open(ARGV[0],"r") do |f|
      f.each_line do |line|
        products << line
      end
    end
    products.each do |product|
      data = product.split(",")
      newproducts.push(Product.new(data[0].strip,data[1].strip,data[2].strip.to_i,data[3].strip.to_i))
    end

    puts "What to sort by?"
    question = gets.strip
    if question == "name"
      newproducts.sort! {|a,b| b.name <=> a.name}
    elsif question == "price"
      newproducts.sort! {|a,b| b.price <=> a.price}
    elsif question =="id"
      newproducts.sort! {|a,b| b.id <=> a.id}
    elsif question == "stock"
      newproducts.sort! {|a,b| b.stock <=> a.stock}
    else
      puts "Wrong Answer."
    end

    #End of File Check
  else
    puts "File #{ARGV[0]} does not exist."
  end

  if ARGV[1] != nil
    File.open(ARGV[1],"w") do |f|
      newproducts.each do |product|
        puts "Added #{product.name} to the file."
        data = {product.id,product.name,product.price,product.stock}
        f.puts(data)
      end
    end
    #End of ARGV check.
  else
    puts "No output file assigned."
  end

  #End of master ARGV check.
else
  puts "No command given."
end