calculator.rb

def calculate(first_number, second_number, operator)
  case operator
  when "+"
    first_number + second_number
  when "-"
    first_number - second_number
  when "*"
    first_number * second_number
  when "/"
    first_number / second_number
  end

  # Same as above
  # if operator == "+"
  #   first_number + second_number
  # elsif operator == "-"
  #   first_number - second_number
  # elsif operator == "*"
  #   first_number * second_number
  # elsif operator == "/"
  #   first_number / second_number
  # end
end

interface.rb

# As the user for a number
# check if input valid
# Store the number given by the user
# As the user for another number
# Store the second number given by the user
# Ask the user for the type of operation
# Store the type of operation
# Execute the operation (+ - / *)
# Show/display result on screen

# ask user if they want to continue

# REGEXP to validate numbers input
# /\A\d+\Z/

# REG to validate operator input
# /\A[+-\/*]\Z/

require_relative "calculator.rb"
require 'pry-byebug'

choice = "yes"

loop do
  puts "Enter first number:"
  print "> "
  first_number = gets.chomp

  until first_number =~ /\A\d+\Z/
    puts "Please type in a valid number:"
    print "> "
    first_number = gets.chomp
  end


  puts "Enter second number:"
  print "> "
  second_number = gets.chomp

  until second_number =~ /\A\d+\Z/
    puts "Please type in a valid number:"
    print "> "
    second_number = gets.chomp
  end

  puts "Choose operation [+][-][*][/]"
  operator = gets.chomp

  until operator =~ /\A[+-\/*]\Z/
    puts "Please choose a valid operator: [+][-][*][/]"
    print "> "
    operator = gets.chomp
  end

  result = calculate(first_number.to_i, second_number.to_i, operator)
  puts "Result: #{result}"

  puts "Do you want to continue? (type 'quit')"
  choice = gets.chomp
  break if choice == "quit"
end

puts "Quitting... Goodbye!!"