Compiler HWK#1 Due date: 2:20pm, March 24, 2005

Write a LEX program to do the following:
   a. Input: an ASCII text file containg a C program code.
   b. Output:
    a stream of the following tokens after striping white spaces, i.e.,
    tab and space. Note tab and space are also tokens, but not reported.

       identifier	      valid C variable name
       int-const	      integer constant (unsigned)
       float-const	      floating point constant (unsigned)
       string		      a valid C-string, e.g., "xyz"
       equal		      ==
       assign		      =
       plus		      +
       minus		      -
       left-paren	      (
       right-paren	      )
       left-{		      {
       right-}		      }
       comma		      ,
       semi-colon	      ;
       new-line		      \n
       others		      a character that is not
			      tab, space, new line or EOF and
			      matches none of the above
   c. if there are conflicts between definitions of tokens, use standard LEX
      tie-breaking scheme.

Example:
Input:
	main(){
		int i;
           @123
		i = i+1;
	}
Output:
	identifier left-paren right-paren left-{ new-line
	identifier identifier semi-colon new-line
	others int-const new-line
	identifier assign identifier plus int-const semi-colon new-line
	right-} new-line

Note: (a) put a space in-between tokens
      (b) put "\n" after new-line, there is no leading/tailing
          spaces in each line
      (c) watch out floating-point constants
      (d) <<EOF>> can be used to match end of file,
          yyterminate() can be used to stop the scanner.
      (e) To submit your homework, send an email to comp05@csie.ntu.edu.tw
          subject: HWK1: your student number and name
                   eg: "HWK1 - B91922xxx ¤ý¤p©ú"
          attachments: one file: B91922xxx.tar.gz
                       files must contain in the current dir
                       after uncompression and untar

This homework MUST execute on Linux or FreeBSD workstations in our department.
Submitting files include a lex file, a Makefile, and optional C codes. The
Makefile MUST supports "make clean" and "make all" for cleaning,
and building the homework. An example of the Makefile can be
obtained from the course web. Do not use the samples without proper
changes.
The name of your executable after "make all" must be "hw1" and takes
input from standard input and writes to standard output.