Perform lexical operations that are usually best implemented with a Finite Automata (or Finite State Machine). Start by writing out the grammar for each problem.

Write a program in Ruby to convert a character representation of a non-negative number to an integer value without using the string-to-integer conversions available in some languages (you must do a character-by-character conversion). Use a separate method to do the actual conversion.

Note the ASCII characters for 0 through 9 are in order,

Do not use hardcoded numbers for ASCII values of digits or any other characters.