Arrays and Hashes
Learn how to create, modify, and access elements in arrays and hashes.
Arrays and Hashes is a free Ruby Academy lesson on CoddyKit. This is lesson 1 of 3. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the Ruby Academy learning path, and your progress syncs across the web and the CoddyKit app. The Ruby Academy course includes 3 lessons in total.
Introduction to Arrays and Hashes
Arrays and Hashes
Ruby provides two main collection types: Arrays and Hashes.
In this lesson, you will learn how to create, modify, and access elements in Arrays and Hashes.
Defining an Array
Arrays store multiple values in an ordered list.
numbers = [1, 2, 3, 4, 5]
puts numbersAccessing Array Elements
You can access elements using their index, starting from 0.
fruits = ['Apple', 'Banana', 'Cherry']
puts fruits[0] # Apple
puts fruits[-1] # CherryAdding Elements to an Array
Use push or << to add elements.
numbers = [1, 2, 3]
numbers << 4 # Adds 4 to the end
puts numbersDefining a Hash
Hashes store key-value pairs.
person = { 'name' => 'Alice', 'age' => 25 }
puts personAccessing Hash Values
Use keys to access values in a hash.
person = { 'name' => 'Alice', 'age' => 25 }
puts person['name'] # AliceAdding New Key-Value Pairs to a Hash
You can add new keys dynamically.
person = { 'name' => 'Alice' }
person['age'] = 25
puts personListing Hash Keys
You can get all keys using the keys method.
person = { 'name' => 'Alice', 'age' => 25 }
puts person.keysCongratulations!
You have learned how to use Arrays and Hashes in Ruby.
Next, you will learn how to iterate over collections using loops and iterators.
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Frequently Asked Questions
Is the “Arrays and Hashes” lesson free?
Yes — any 3 lessons of the Ruby Academy learning path, including “Arrays and Hashes”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The Ruby Academy course includes 3 lessons in total.
What will I learn in “Arrays and Hashes”?
Learn how to create, modify, and access elements in arrays and hashes. You practise Ruby Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Ruby Academy?
No prior experience is required. Ruby Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.
How long does the “Arrays and Hashes” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Ruby Academy lesson?
Yes. Every Ruby Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Arrays and Hashes
- Iterating Over Collections
- Useful Array and Hash Methods