Variables & Types

Ruby is a dynamic, beginner-friendly programming language, and variables are how you store and label the data your program works with — text, numbers, true/false, and "nothing".

Learn Variables & Types in our free Ruby course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free Ruby course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

By the end of this lesson you'll assign variables, recognise Ruby's core types, check a value's class, and convert between strings and numbers.

What You'll Learn in This Lesson

1️⃣ Assigning Variables

You create a variable by writing a name, an = , and a value. Unlike many languages, you don't declare a type — Ruby reads the value and works out the type itself. Here are the five values you'll meet most: a String (text), an Integer (whole number), a Float (decimal), a Boolean ( true / false ), and nil (nothing).

We used .inspect on nil because plain puts nil prints a blank line — .inspect shows the value clearly as nil .

2️⃣ Types and Converting Between Them

Every value knows its own type — ask with .class . Because Ruby is dynamically typed , a variable can point to a String now and a number later. When data crosses a boundary (like user input, which always arrives as text), you convert it with .to_i (to Integer), .to_f (to Float), or .to_s (to String).

Your turn. Build a small player profile. Replace the three TODO values, keeping the right type for each, then run it.

Write a tiny miles-to-kilometres converter using a Float and interpolation. Run it with ruby convert.rb and check against the example.

📋 Quick Reference — Variables & Types

Practice quiz

• Browse all free courses
• Cheat sheets & quizzes
• Coding dictionary