undefined local variable ruby

Question

Here is my class:

class Money
  def initialize(dollars, quarters, dimes, nickels, pennies)
    @coins = [ {:coin => dollars,  :price => 100},
               {:coin => quarters, :price => 25},
               {:coin => dimes,    :price => 10},
               {:coin => nickels,  :price => 5},
               {:coin => pennies,  :price => 1} ]
  end
  def count
    total = 0.00
    coins.each do |coin|
      next if coin[:price] == 0
      total += coin[:coin] * coin[:price]
    end
    total / 100
  end
end

and I am testing it like this:

money = Money.new( 5, 1, 2, 1, 0 )
puts "$%.2f" % money.count

I am receiving an error:

money.rb:12:in `count': undefined local variable or method `coins' for #<Money:0x2567310> (NameError)
    from money.rb:34:in `<main>'

which points to the line coins.each do |coin| and doesn't make sense to me because I thought that, if I prefix a variable with @, I could use it throughout my objects's methods (it will not carry over to a different object).

I got this working using different code that does:

@dollar = dollar
@quarter = quarter
...

for my initialize method (my count method was radically different), but now I am trying to create an array of hash tables so that I could refactor my count method.

Any help will be appreciated.

Henrik Andersson · Accepted Answer · 2013-05-06 07:41:08Z

4

In your count() method refer to coins as @coins. Otherwise you've created a variable only available to the method your in and not referencing your instance variable that you created in your initialize()

So that it reads:

def count
    total = 0.00
    @coins.each do |coin|
        next if coin[:price] == 0
        total += coin[:coin] * coin[:price]
    end
    total / 100
end

answered May 6, 2013 at 7:41

Henrik Andersson

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2 Comments

randy newfield Over a year ago

wow... i feel slightly dumbfound. I always though that you did not need to include the @ sign in the variable name, as I have used lines such as #{dollars} and it worked. Thanks for teaching me this simple mistake.

vgoff Over a year ago

@randynewfield what you don't need to use when you do the string interpolation for an instance variable is the brackets. Such that you can do this "#@count"

MarioDS · Accepted Answer · 2013-05-06 07:41:20Z

2

If you create an instance variable (using @), you must always reference it with @.

def count
  total = 0.00
  @coins.each do |coin| #Here was your error
    next if coin[:price] == 0
    total += coin[:coin] * coin[:price]
  end
  total / 100
end

answered May 6, 2013 at 7:41

MarioDS

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