We need to implement a lexical analyzer which is able to recognize octal and decimal
numbers with the following requirements.
● An input number starts with a + or - sign.
● An octal number starts with a 0 and can continue with an arbitrarily number of
digits. An octal number started with more than one 0 is not an acceptable
number. Note: digits used in an octal number are between 0 and 7.
● A decimal number starts with any digit except 0 and can continue with an
arbitrarily number of digits. Note: digits used in a decimal number are between 0
and 9.
● 0 is an acceptable number, no matter whether we accept it as a decimal or as an
octal number.
1. Write a context free grammar or a regular grammar to satisfy the requirements.
Note: the alphabet of this language is {+, -, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}.
2. Create a finite automaton for the grammar.
Here are some examples of accepted input:
{+0, +9803467, -184, -04650, ...}
Here are some examples of rejected input:
{-03489, -00, +, -034-21, 146802, ...}