# Basic data types and variables name = "Alice" age = 30 is_student = true pi_value = 3.14159 numbers = [1, 2, 3, 4, 5] user_data = { "name" => "Bob", "age" => 25, :city => "New York" } puts "Hello, #{name}! You are #{age} years old." # Control flow: if/else, unless, case if age >= 18 puts "You are an adult." elsif age >= 13 puts "You are a teenager." else puts "You are a child." end unless is_student puts "This person is not currently a student." end grade = 'B' case grade when 'A' puts "Excellent!" when 'B' puts "Good job!" when 'C' puts "Pass." else puts "Needs improvement." end # Loops: while, until, for, each count = 0 while count < 3 puts "While loop iteration: #{count}" count += 1 end num = 5 until num == 0 puts "Until loop iteration: #{num}" num -= 1 end for number in numbers puts "For loop number: #{number}" end numbers.each do |n| puts "Each loop number: #{n}" end # Methods and blocks def greet(person_name) puts "Greetings, #{person_name}!" end greet("Charlie") def calculate_sum(a, b) a + b # Implicit return end result = calculate_sum(10, 20) puts "Sum: #{result}" # Blocks with parameters [10, 20, 30].map do |x| x * 2 end.each { |doubled| puts "Doubled: #{doubled}" } # Classes and Objects class Person attr_accessor :name, :age # Creates getter and setter methods def initialize(name, age) @name = name @age = age end def introduce "Hi, my name is #{@name} and I am #{@age} years old." end end my_person = Person.new("David", 40) puts my_person.introduce my_person.age = 41 puts "David's new age: #{my_person.age}" # Inheritance class Student < Person attr_accessor :student_id def initialize(name, age, student_id) super(name, age) # Calls the parent class's initialize method @student_id = student_id end def introduce "#{super} My student ID is #{@student_id}." end end my_student = Student.new("Eve", 22, "S12345") puts my_student.introduce # Modules module MathOperations def self.add(x, y) x + y end def self.subtract(x, y) x - y end end puts "Module addition: #{MathOperations.add(5, 3)}" # Error handling begin # This might raise an error 10 / 0 rescue ZeroDivisionError => e puts "Caught an error: #{e.message}" ensure puts "This block always executes." end # Symbols, Strings, and Arrays symbol_example = :my_symbol string_example = "This is a string." array_example = [1, "two", :three, true] puts "Symbol: #{symbol_example}, String length: #{string_example.length}" puts "Array first element: #{array_example[0]}, last: #{array_example.last}" # Hashes hash_example = { key1: "value1", key2: "value2" } puts "Hash value for key1: #{hash_example[:key1]}" hash_example[:key3] = 123 puts "All hash keys: #{hash_example.keys}" # Regular expressions if "hello world" =~ /world/ puts "Pattern found!" end # File operations (brief example) File.open("example.txt", "w") do |file| file.puts "Hello from Ruby!" end puts "File 'example.txt' created."