Ruby

Ruby, created in 1995. https://www.ruby-lang.org/

Example

demo.rb

puts "=== Ruby Demo: 11 Examples ===\n\n"

# 1. Hello World
puts "1) Hello World:"
puts "Hello, world!\n\n"

# 2. Variables and arithmetic
puts "2) Variables & Arithmetic:"
a = 5
b = 3
puts "a = #{a}, b = #{b}, sum = #{a + b}\n\n"

# 3. Arrays
puts "3) Arrays:"
fruits = ["apple", "banana", "cherry"]
puts "First fruit: #{fruits[0]}"
puts "All fruits: #{fruits.join(', ')}\n\n"

# 4. Hashes
puts "4) Hashes:"
ages = { "Alice" => 25, "Bob" => 30 }
puts "Alice is #{ages["Alice"]} years old\n\n"

# 5. Conditionals
puts "5) Conditionals:"
if a > b
  puts "#{a} is greater than #{b}\n\n"
else
  puts "#{b} is greater or equal to #{a}\n\n"
end

# 6. Loops
puts "6) Loops:"
(1..3).each do |i|
  puts "Loop iteration #{i}"
end
puts

# 7. Methods
puts "7) Methods:"
def greet(name)
  "Hello, #{name}!"
end
puts greet("Ruby User")
puts

# 8. File handling
puts "8) File Handling (write & read):"
filename = "demo.txt"

# Write
File.open(filename, "w") do |f|
  f.puts "This is a test file."
end

# Read
File.open(filename, "r") do |f|
  f.each_line do |line|
    puts "Read: #{line}"
  end
end
puts

# 9. Regular expressions
puts "9) Regular Expressions:"
text = "Ruby is powerful"
if text =~ /powerful/
  puts "Match found in text!\n\n"
end

# 10. Command-line arguments
puts "10) Command-line Arguments:"
if ARGV.any?
  puts "Arguments passed: #{ARGV.join(' ')}\n\n"
else
  puts "No arguments provided\n\n"
end

# 11. Method using shift
puts "11) Method with shift:"
def add_numbers(*args)
  x = args.shift   # first argument
  y = args.shift   # second argument
  x + y
end

result = add_numbers(10, 20)
puts "10 + 20 = #{result}"

puts "\n=== End of Demo ==="

Famous book

• “Pickage book”

Famous library/framework

• Ruby on Rails: https://rubyonrails.org/

Similar to Perl and Python