In The C Programming Language (Kernighan and Ritchie), an integer constant is defined as follows. "An integer constant consisting of a sequence of digits is taken to be octal if it begins with 0 (digit zero), decimal otherwise. Octal constants do not contain the digits 8 or 9. A sequence of digits preceded by 0x or 0X (digit zero) is taken to be a hexadecimal integer. The hexadecimal digits include a or A through f or F with values 10 through 15. "An integer constant may be suffixed with the letter u or U, to specify that it is unsigned. It may also be suffixed by the letter l or L to specify that it is long."

(a) Write a regular expression that generates C integer constants as described above. (Of course you can break the solution down into a regular expression with several named parts if it makes things easier to write and read.)

(b) Draw a DFA that recognizes integer constants as defined by your solution to part (a).