Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] Better option to read a file
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Markus Mottl <markus@o...>
Subject: Re: [Caml-list] Better option to read a file
Hi,

I usually use one of the two functions below to read in whole strings.
Function "read_file" does the obvious: read a file as fast as possible
into a string.

Function "read_channel" reads a channel of unbounded size (as long as the
maximum string length is not exceeded, of course).  It also takes the
optional argument "buf_size", which you can set depending on the kind
of channel you read from (the default 4096 bytes are somewhat optimal
when reading from files on Linux).

---------------------------------------------------------------------------
let rec copy_lst res ofs = function
  | [] -> res
  | (str, len) :: t ->
      let pos = ofs - len in
      String.unsafe_blit str 0 res pos len;
      copy_lst res pos t

let read_channel ?(buf_size = 4096) =
  let rec loop len lst ch =
    let buf = String.create buf_size in
    let n = input ch buf 0 buf_size in
    if n <> 0 then loop (len + n) ((buf, n) :: lst) ch
    else copy_lst (String.create len) len lst in
  loop 0 []

let read_file name =
  let file = open_in name in
  let size = in_channel_length file in
  try
    let buf = String.create size in
    really_input file buf 0 size;
    close_in file;
    buf
  with exc ->
    (try close_in file with _ -> ());
    raise exc
---------------------------------------------------------------------------

Regards,
Markus Mottl

-- 
Markus Mottl          http://www.oefai.at/~markus          markus@oefai.at

-------------------
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