MrBean83

class Sudoku
  def initialize(string)
    string = string.split('')

    @board = Array.new(9){Array.new(9)}

    @board.each_index do |row|
      @board[row].each_index do |column|
        @board[row][column] = string.shift.to_i
        if @board[row][column] == 0

MrBean83

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

MrBean83

# Determine whether a string contains a Social Security number.
def has_ssn?(string)
  /\d{3}-\d{2}-\d{4}/.match(string)
end

# Return the Social Security number from a string.
def grab_ssn(string)
  def grab_ssn(string)
  if /\d{3}-\d{2}-\d{4}/.match(string)
    string.match(/\d{3}-\d{2}-\d{4}/).to_s

MrBean83

class RPNCalculator
  def evaluate(rpn)
    rpn = rpn.split
    array = rpn.inject([]) do |array, i|
      if i.match(/\d+/)
        array = i.to_i
      else
        eq = array.pop(2)
        case
          when i == "+"

MrBean83

class CreditCard
  def initialize(card_number)
    @card = card_number.to_s
    if @card.length != 16
      raise ArgumentError.new("This is not a valid credit card number.")
    end
  end
  
  def check_card
    chars = @card.split(//)

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?

MrBean83

class GuessingGame
  def initialize(answer)
    @answer = answer
  end
 
  def guess(guess)
    @guess = guess
    result = nil
 
    case guess

MrBean83

class Die
  attr_accessor :labels

  def initialize(labels)
    unless labels.length > 0
      raise ArgumentError.new("Where's your strings?")
    end
    @labels = labels
  end

MrBean83

def times_table(rows)
  1.upto(rows).each do |line|
    1.upto(rows).each do |num| 
      print "#{line*num} " 
    end 
    print "\n" 
  end
end

MrBean83

def is_fibonacci?(i)
  n = i * Math.sqrt(5)
  n1 = Math.sqrt((5*(i**2)+4))  
  n2 = Math.sqrt((5*(i**2)-4))
  
  if (i == 1 || i == 0)
    return true
  elsif (n1 % 1 == 0) || (n2 % 1 == 0)
    return true
  else