From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id CAA03570; Mon, 10 Nov 2003 02:49:08 +0100 (MET)
X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f
Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id CAA03501 for <caml-list@pauillac.inria.fr>; Mon, 10 Nov 2003 02:49:07 +0100 (MET)
Received: from herd.plethora.net (herd.plethora.net [205.166.146.1])
	by concorde.inria.fr (8.11.1/8.11.1) with ESMTP id hAA1n6124769
	for <caml-list@pauillac.inria.fr>; Mon, 10 Nov 2003 02:49:06 +0100 (MET)
Received: from bhurt.plethora.net (bhurt.plethora.net [205.166.146.49])
	by herd.plethora.net (8.11.6/8.10.1) with ESMTP id hAA1n1C20749;
	Sun, 9 Nov 2003 19:49:02 -0600 (CST)
Date: Sun, 9 Nov 2003 20:47:56 -0600 (CST)
From: Brian Hurt <bhurt@spnz.org>
X-X-Sender: bhurt@localhost.localdomain
To: Michael Hoisie <mbh@OCF.Berkeley.EDU>
cc: caml-list@pauillac.inria.fr
Subject: Re: [Caml-list] Arbitrarily throwing End_of_file
In-Reply-To: <20031109171638.42cd6807.mbh@ocf.berkeley.edu>
Message-ID: <Pine.LNX.4.44.0311092036210.5009-100000@localhost.localdomain>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Loop: caml-list@inria.fr
X-Spam: no; 0.00; caml-list:01 arbitrarily:01 26,000:99 printf:01 printf:01 recursion:01 recursion:01 byte:01 rec:01 rec:01 nov:01 30,000:97 eof:02 eof:02 bytes:02 
Sender: owner-caml-list@pauillac.inria.fr
Precedence: bulk

On Sun, 9 Nov 2003, Michael Hoisie wrote:

> I have a file which is approximately 278,440 lines of text (more
> specifically, it is the result of doing 'ls -lAR /')

-l lists the file size in *bytes*, not lines.  Use 'wc -l longfile.dat' to
determine the number of lines.  If each line is ~10.6 bytes long
(including the EOLN) then a 278,000 byte file will be about 26,000 lines
long.  The -A means "almost all" (everything except . and ..), and the R
means recursive (list subdirectories as well).

> 
> I was trying to write this relatively simple program to analyze it but
> it seems that End_of_file was thrown very early.
> 
> To test, it, I made a simple function:  
> 
> let rec count_lines file n =
>     try let str = input_line file in
>     count_lines file (n + 1)
>     with End_of_file -> Printf.printf "The file is %d\n lines long" n

This function isn't tail recursive- the function's call to itself is
within a try/with block, which breaks the tail recursion.  That isn't the
problem you're hitting, but you're not far from hitting it.  I generally
hit it about 30,000 functions deep or so.  Try the following instead:

let rec count_lines file n =
    let line, eof = try (input_line file), false
                   with End_of_file -> "", true
    in
    if not eof then
        begin
            (* do something with line here *)
            count_lines file (n + 1)
        end
    else
        n

let file = open_in "longfile.dat" in
Printf.printf "The file is %d lines long.\n" (count_lines file 0)

Note that the tail recursion is now outside of the try/with block, and 
this function will work with any length file.

Brian


-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners