Henry Nichols MrBean83

Implementing a Reverse Polish notation calculator in Ruby

A couple weeks ago I had a go at implementing an RPN calculator in Ruby. I knew I wanted the calculator to function by popping operands out of an array populated with the values of the input expression, operating upon the operands with the appropriate operator, and pushing the result back into the stack of operands.

I was able to implement this in version 1, but it took forever and the resulting code was not very beautiful. Why?

I started coding before I had a thorough understanding of RPN

Wait, 20 10 5 4 + * - is what now?

	//------------------------------------------------------------------------------------------------------------------
	// YOUR CODE: Create your Zoo "object literal" and Animal "constructor" and "prototypes" here.
	//------------------------------------------------------------------------------------------------------------------

	function Animal(name, number_of_legs) {
	this.name = name;
	this.number_of_legs = number_of_legs;
	}

	Animal.prototype.identify = function(){

	<!doctype html>
	<html>

	<head>
	<link rel="stylesheet" href="http://cdn.jsdelivr.net/normalize/2.1.0/normalize.css">
	<link rel="stylesheet" href="main.css">
	<link rel="stylesheet" href="http://fonts.googleapis.com/css?family=Open+Sans:300,400,600,700,800">
	<link rel="stylesheet" href="http://fonts.googleapis.com/css?family=Lato:100,900">
	<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/font-awesome/3.0.2/css/font-awesome.min.css">
	</head>

	class RomanNumerals
	def initialize
	self.re_pop
	end

	def converter(test_number, discard = 0, key = @roman_numbers.keys.first)
	return "" if test_number == 0
	(@roman_numbers[key] * (test_number / key)) +
	converter(test_number % key, @roman_numbers.delete(key))
	end

	def get_grade(grade)
	average = grade.to_i

	case average
	when 90..100
	"A"
	when 80...90
	"B"
	when 70...80
	"C"