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Ruby Ruby Booleans Build a Simple Todo List Program Finding Array Items

Devin Scheu
Devin Scheu
66,191 Points

Help With Ruby

Question: Fill in the find_index method to return the index of a todo item in the @todo_items array given the name. The method should return the index of the item if the item is found and nil if it is not found.

My Code:

todo_list.rb
class TodoList
  attr_reader :name, :todo_items

  def initialize(name)
    @name = name
    @todo_items = []
  end

  def add_item(name)
    todo_items.push(TodoItem.new(name))
  end

  def find_index(name)
    index = 0
    found = false
    todo_items[name]
  end

end

6 Answers

Jason Seifer
STAFF
Jason Seifer
Treehouse Guest Teacher

Stone Preston Devin Scheu The code looks like it would work but it's a bit deceiving! If we were going for an index of the String "name" in the todo_items array, then the index method would work. However, when we add an item to the todo_items array, in the add_item method, we're creating a new TodoItem with that information. The index method looks for equality in an array and a string instance is not going to be equal to a TodoItem instance. Therefore, we need to figure out how to find TodoItem in the todo_items array.

Devin Scheu
Devin Scheu
66,191 Points

Yes, thanks for clearing it up for me Jason. :)

ttaleg
ttaleg
9,830 Points

did anyone figure this out? I cant either

I answered with the following code and it worked (basically the same as what was done in the preceding video lessons):

def find_index(name)
    index = 0
    found = false
    todo_items.each do |todo_item|
        if todo_item.name == name
            found = true
        end
        if found
            break
        else
            index += 1
        end
    end
    if found
        return index
    else
        return nil
    end
end

Took me a few tries to actually get it right - with this challenge, there are a lot of small moving parts, so it's important to do a thorough check and de-bug. I noticed that mine wasn't passing for a few tried simply because I had an extra "end" at the bottom, which was throwing the whole thing off.

I think Treehouse should at least give the option for some sort of answer key to the challenge problems, so that getting stuck on something like this doesn't completely derail progress. It can be very discouraging, and waiting days, weeks, or longer for an answer definitely ain't good for getting into a coding groove. Just a thought - love the program/teachers, and the content and delivery is great!!

Thanks and good luck! -Peter *loyal fan and user

Jason Seifer Ryan Carson

Joshua Paulson
Joshua Paulson
37,085 Points

Love when people copy paste code that doesn't work when they say it worked for them. Really helpful.

Stone Preston
Stone Preston
42,016 Points

looking at the ruby array documentation there is a method called index you can use.

Returns the index of the first object in self such that the object is == to obj. If a block is given instead of an argument, returns index of first object for which block is true. Returns nil if no match is found

so you should be able to use that easily

def find_index(name)
    todo_items.index(name)
end

However, the challenge does not accept that for some reason. Jason Seifer any idea why that does not work?

Devin Scheu
Devin Scheu
66,191 Points

Okay so I changed the code to and if statement, and used the concept you showed me. But im still getting it wrong, I often get confused between the syntax's of different languages. So what am I doing wrong,.

  def find_index(name)
    index = 0
    found = false
    if (index > 0)
    todo_items.find_index(name)
    else
      nil
    end
  end

Can anyone else help with this question please? I cannot figure it out either.

Vlad Filiucov
Vlad Filiucov
10,665 Points

i don't get this part

        if todo_item.name == name
            found = true

Where does this ".name" method come from?