[Applied] Build a Simple Inventory Management Tool

In this lesson you will combine the classes, hashes, and loops you have learned into a simple inventory management program, pulling everything together. This is for anyone searching for "Ruby inventory management how to build".

Combine the classes, hashes, and loops you have learned so far into a program that tracks stock levels. Real application development works the same way: small pieces combined into something larger.

The sample code initialises @items inside the Inventory class with Hash.new(0). That is a neat, idiomatic Ruby touch: a hash that returns 0 for a missing key, so the first addition needs no special handling.

A common stumbling block for beginners is taking in a program where several features interlock. Check one method at a time - add first, then remove - before following how they work together, and it becomes much easier to grasp.

Well done for getting this far. The Ruby fundamentals from these lessons apply directly to real work, including building web applications with Ruby on Rails.

📖 Reference code

class Inventory
  def initialize
    @items = Hash.new(0)
  end
  def add(name, qty)
    @items[name] += qty
  end
  def remove(name, qty)
    @items[name] -= qty
  end
  def show
    @items.each { |name, qty| puts "#{name}: #{qty}" }
  end
end

inv = Inventory.new
inv.add("apple", 10)
inv.add("orange", 5)
inv.remove("apple", 3)
inv.show

✍️ Your code

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