simple dollars to decimal conversions in Ruby

dollars_to_big_d.rb

    def format_as_dollars(c)
      unless c.nil?
        c = (c * 100).round / 100
        "$%.2f" % c
      end
    end
    
    def decimal_from_currency(c)
      if c =~ /\$/
        c = c[1, c.length]
      end
      BigDecimal(c.to_s)
    end