calculator.rb

def say(msg)
  puts "=> #{msg}"
end

loop do

  say "What's the first number?"
  num1 = gets.chomp

  say "What's the second number?"
  num2 = gets.chomp

  operator = ''

  loop do 
    puts "1) add 2) subtract 3) multiply 4) divide"
    operator = gets.chomp
    break if %w(1 2 3 4).include?(operator)
    puts "Please choose one of the following options:"
  end

  calc_num1 = num1.to_f
  calc_num2 = num2.to_f

  case 
  when operator == '1'
    result = calc_num1 + calc_num2
  when operator == '2'
    result = calc_num1 - calc_num2
  when operator == '3'
    result = calc_num1 * calc_num2
  when operator == '4'
    while calc_num2 == 0.0
      puts "You can't divide by 0. Your fist number is #{num1}. Please choose a new second number to divide by."
      num2 = gets.chomp
      calc_num2 = num2.to_f
    end
    result = calc_num1 / calc_num2
  end

  #Output result.  If resulting float is of the form 'n.0', prints result without the trailing 0.
  if result/result.to_i == 1.0
    puts "The result is #{result.to_i}."
  else
    puts "The result is #{result}."
  end

  say "Do you want to do more math? (y or n)"
  break if gets.chomp.downcase != 'y'

end