meet it

Every item has a numbered spot, starting at 0.

Each item sits at a numbered position called its . Ruby starts counting at 0, so the first item is fruit[0]. Count back from the end with minus numbers: fruit[-1] is the last item.

Put a new value at an index to replace that item: fruit[1] = "pear". To a new item onto the end, use << or .push.

Ask for an index with no item there, and Ruby hands back , its word for nothing at all. puts nil shows an empty line.

fruit = ["apple", "banana", "cherry"]
puts fruit[0]
puts fruit[-1]
fruit[1] = "pear"
fruit << "lemon"
p fruit

fruit << "lemon" and fruit.push("lemon") do the same job.

guess first

Which colour is at index 1?

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

colours = ["red", "green", "blue"]
puts colours[1]

your turn

Your turn. Run a pet shop.

In the first blank, type a pet to add to the end. In the second, type a new pet to take the place of the cat. Then press run.

Your code

press run to see what happens

fix it

This should show the last fruit, but shows nothing. Fix it!

Broken code to fix

press run to see what happens

Nothing shows. Which index does the last item really have?
Indexes start at 0, so three items sit at 0, 1 and 2. Index 3 has nothing, so you get nil.
Change fruit[3] to fruit[2], or to fruit[-1], then press run.

nailed it

you can reach any item you like. :D

The first item is at index 0. The last is at -1.
Replace an item with fruit[1] = "pear".
Add to the end with << or .push.

new words in your collection

index
push
nil

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