Simple file i/o script question (newbie)

Question

OK - I'm going brain dead.  I'm new to applescript and my script works great except for one piece.  I need to keep a count of how many iterations my script does each time I use it, so my thought was to have a file called serial.txt that starts with a value of 0.  The script would open this file and set a variable to its value (say iterationnum).  Upon each iteration within the script it would increment iterationnum.  Upon script completetion, it would replace the value in serial.txt with the new value of the variable iterationnum and close the file.  Next time I run the script, the value of iterationnum would continue where I left off.  Iternationnum could go as high as 100,000 or so.
it's simple enough but I can't seem to get the i/o syntax correct.  Would one of you seasoned gurus be kind enough to post an example of this? 
Your time is very much appreciated

Answer 1

If you really want to do it as a file here is some code to get you started
-- set the file path and file name and open the file for writing
-- will create it if not already there
set theFile to (path to desktop as text) & "ASCtest"
set fd to open for access theFile with write permission
-- Try to read the file the first time it will error nothing to read
-- catch the error and set the count to 0
try
          set runCount to read fd
on error enum --  first time no data read
          set runCount to 0
end try
-- increment runCount
set runCount to runCount + 1
-- Go back to the beginning of the file and
-- write out the new run count.
try
  set eof of fd to 0
  write runCount as string to fd
on error enum
  display alert enum
  close access fd
end try
-- close the file
close access fd
display alert "runCount: " & runCount