Ruby Basics for Beginners

Introduction

Ruby is an elegant, expressive programming language that prioritizes developer happiness. In this guide, we’ll learn the fundamentals of Ruby that you’ll need to start building Rails applications.

Getting Started with Ruby

What is Ruby?

Ruby is a dynamic, object-oriented programming language created by Yukihiro "Matz" Matsumoto. It’s designed to be:

Intuitive and natural to read
Fun and productive to write
Powerful and flexible

Interactive Ruby (IRB)

Open your terminal and type irb to start an interactive Ruby session:

$ irb
irb(main):001:0> 2 + 2
=> 4
irb(main):002:0> "hello".upcase
=> "HELLO"

Tip	IRB is great for experimenting with Ruby code and testing quick ideas.

Ruby Fundamentals

Variables and Data Types

Variables in Ruby don’t need explicit declaration:

# Numbers
age = 25          # Integer
price = 19.99     # Float

# Strings
name = "Ruby"
greeting = 'Hello'

# Booleans
is_active = true
has_errors = false

# Arrays
numbers = [1, 2, 3, 4, 5]
names = ["Alice", "Bob", "Charlie"]

# Hashes
person = {
  name: "John",
  age: 30,
  city: "Portland"
}

String Manipulation

Strings in Ruby are incredibly flexible:

# String concatenation
first_name = "Ruby"
last_name = "Developer"
full_name = first_name + " " + last_name
=> "Ruby Developer"

# String interpolation
greeting = "Hello, #{first_name}!"
=> "Hello, Ruby!"

# Common string methods
name = "ruby"
name.upcase        # => "RUBY"
name.capitalize    # => "Ruby"
name.reverse       # => "ybur"
name.length        # => 4

Working with Arrays

Arrays are ordered collections of objects:

# Creating arrays
numbers = [1, 2, 3, 4, 5]
fruits = %w[apple banana orange]  # => ["apple", "banana", "orange"]

# Common array operations
numbers.first           # => 1
numbers.last            # => 5
numbers.length          # => 5
numbers.include?(3)     # => true
numbers << 6            # => [1, 2, 3, 4, 5, 6]

# Array iteration
fruits.each do |fruit|
  puts "I love #{fruit}!"
end

# Array transformation
doubled = numbers.map { |n| n * 2 }
=> [2, 4, 6, 8, 10]

# Array filtering
even_numbers = numbers.select { |n| n.even? }
=> [2, 4, 6]

Working with Hashes

Hashes are collections of key-value pairs:

# Creating hashes
person = {
  name: "John",
  age: 30,
  city: "Portland"
}

# Accessing hash values
person[:name]      # => "John"
person.fetch(:age) # => 30

# Adding/updating values
person[:email] = "john@example.com"
person[:age] = 31

# Iterating over hashes
person.each do |key, value|
  puts "#{key}: #{value}"
end

Control Flow

Conditionals

# If statements
if age >= 18
  puts "You're an adult"
elsif age >= 13
  puts "You're a teenager"
else
  puts "You're a child"
end

# Unless statement (opposite of if)
unless is_admin
  puts "Access denied"
end

# Case statement
case status
when "pending"
  process_order
when "shipped"
  send_notification
else
  log_error
end

Loops and Iteration

# While loop
counter = 0
while counter < 5
  puts counter
  counter += 1
end

# Each loop (preferred)
5.times do |i|
  puts i
end

# Range iteration
(1..5).each do |n|
  puts n
end

Methods

Methods are reusable blocks of code:

# Basic method
def greet(name)
  "Hello, #{name}!"
end

# Method with default parameter
def calculate_total(price, tax_rate = 0.1)
  price + (price * tax_rate)
end

# Method with multiple parameters
def create_user(name:, email:, age: nil)
  puts "Creating user: #{name} (#{email})"
end

# Calling methods
greeting = greet("Ruby")
total = calculate_total(100)
create_user(name: "John", email: "john@example.com")

Classes and Objects

Creating a Class

class Person
  attr_accessor :name, :age

  def initialize(name, age)
    @name = name
    @age = age
  end

  def introduce
    "Hi, I'm #{name} and I'm #{age} years old."
  end

  def birthday
    @age += 1
  end
end

# Using the class
person = Person.new("Ruby", 25)
puts person.introduce
person.birthday
puts person.age  # => 26

Practical Examples

Building a Todo List

class TodoList
  def initialize
    @tasks = []
  end

  def add_task(description)
    @tasks << {
      id: next_id,
      description: description,
      completed: false
    }
  end

  def complete_task(id)
    task = find_task(id)
    task[:completed] = true if task
  end

  def list_tasks
    @tasks.each do |task|
      status = task[:completed] ? "✓" : " "
      puts "[#{status}] #{task[:description]}"
    end
  end

  private

  def next_id
    @tasks.length + 1
  end

  def find_task(id)
    @tasks.find { |task| task[:id] == id }
  end
end

# Using the TodoList
list = TodoList.new
list.add_task("Learn Ruby")
list.add_task("Build Rails App")
list.complete_task(1)
list.list_tasks

Best Practices

Ruby Style Guide

Use 2 spaces for indentation
Use snake_case for methods and variables
Use CamelCase for classes and modules
End files with a newline
Avoid unnecessary comments
Keep methods small and focused

Common Conventions

Prefer each over for loops
Use string interpolation over concatenation
Use symbols instead of strings for hash keys
Follow the principle of least surprise

Next Steps

Now that you understand Ruby basics, you’re ready to:

Explore more advanced Ruby concepts
Start learning Ruby on Rails
Build practice projects
Join Ruby communities

Additional Resources

Tip	Practice these concepts in IRB as you learn them. The best way to learn Ruby is by writing Ruby!

Warning

Remember that Ruby is very flexible, but with great power comes great responsibility. Always follow Ruby conventions and best practices.