Career Prep Assignment 7

calculator.rb

equation = ARGV[0].dup

my_dear = equation.scan("*").count + equation.scan('/').count
aunt_sally = equation.scan("+").count + equation.scan('-').count

def operate(operation, number1, number2)
  case operation
  when '/'
    return (number1.to_i / number2.to_i).to_s
  when '*'
    return (number1.to_i * number2.to_i).to_s
  when '+'
    return (number1.to_i + number2.to_i).to_s
  when '-'
    return (number1.to_i - number2.to_i).to_s
  else
    puts "ERROR!"
  end
end

my_dear.times do
  division_index = equation.index('/')
  multiplication_index = equation.index('*')
  if(division_index && multiplication_index)
    if(division_index < multiplication_index)
      spot = division_index
      operation = '/'
    else
      spot = multiplication_index
      operation = '*'
    end
  elsif division_index
    spot = division_index
    operation = '/'
  else
    spot = multiplication_index
    operation = '*'
  end
  number1 = equation[spot - 1]
  number2 = equation[spot + 1]
  equation.sub!("#{number1}#{operation}#{number2}", operate(operation, number1, number2))
end


aunt_sally.times do
  subtraction_index = equation.index('-')
  addition_index = equation.index('+')
  if(subtraction_index && addition_index)
    if(subtraction_index < addition_index)
      spot = subtraction_index
      operation = '-'
    else
      spot = addition_index
      operation = '+'
    end
  elsif subtraction_index
    spot = subtraction_index
    operation = '-'
  else
    spot = addition_index
    operation = '+'
  end
  number1 = equation[spot - 1]
  number2 = equation[spot + 1]
  equation.sub!("#{number1}#{operation}#{number2}", operate(operation, number1, number2))
end

puts equation