Compiler HWK#1 Due date: 2:20pm, March 18, 2004

1. Read LEX man pages and find out the meanings of the following special
characters.
      ^ ?  .  (  )  $  {  }  %  <  >

2. Write a LEX program to do the following:
   a. Input: an ASCII text file
   b. Output:
      Copy the file with the following two modifications.
      (1) replace an integer spelled out in English into
      Arabic numbers if this number is between 0 and 99.
      (2) replace an integer in Arabic form into its English equivalent.
      The English equivalent are lower cases separated by
      one blank if needed.
      (3) No token contains a newline.
      Each token is spearated by blank or newline.
      The file is ended with a newline.

Example:
Input: <I don't receive 51 letters. I received thirty one books.>
Output:<I don't receive fifty one letters. I received 31 books.>

Note: (a) "<" and ">" are not part of the input and output.
      (b) Arabic numbers have no leading zeros, ie, 012 is illegal.
      (c) English words are separated by either a single blank (no tabs)
          or a newline. Characters can be uppercase/lower cases or mixing.
      (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 comp04@csie.ntu.edu.tw
          subject: HWK1: your student number and name
                   eg: "HWK1 - B90902xxx 王小明"
          attachments: two files
                       first file: your first homework in TEXT, PS or PDF
                                   format
                       second file: .tar.gz format
                                   files must contain in the current dir
                                   after uncompression and untar
       (f) 一個擺在工作站上簡單的script, 可以讓同學測試
         測試的方法是在工作站上執行
         /home/course/comp04/hw1/test.sh YOUR_EXECUTABLE

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", "make all", and "make test" for cleaning,
building, and testing the homework. An example of the Makefile can be obtained
from the course web.