From: "Mattias Waldau" <mattias.waldau@abc.se>
To: "'Siegfried Gonzi'" <siegfried.gonzi@stud.uni-graz.at>,
<caml-list@inria.fr>
Subject: RE: [Caml-list] Reading a file
Date: Tue, 20 May 2003 12:21:10 +0200 [thread overview]
Message-ID: <020c01c31eb9$8c376710$0200a8c0@gateway> (raw)
In-Reply-To: <3EC9EA84.3070404@stud.uni-graz.at>
If the files are not of megabyte size, I just read
them into a string. Very fast.
(** return the contents of filename as a string *)
let read_as_string filename =
(* read at most len chars into string s, return the number of chars
read *)
let rec my_input ic s ofs len =
if len <= 0 then ofs else begin
let r = input ic s ofs len in
if r = 0
then ofs
else my_input ic s (ofs+r) (len-r)
end in
let ic = open_in_bin filename in
let max_size = in_channel_length ic in
let buf = String.create max_size in
let read_chars = my_input ic buf 0 max_size in
close_in ic;
String.sub buf 0 read_chars ;;
> -----Original Message-----
> From: owner-caml-list@pauillac.inria.fr
> [mailto:owner-caml-list@pauillac.inria.fr] On Behalf Of
> Siegfried Gonzi
> Sent: den 20 maj 2003 10:43
> To: 'caml-list@inria.fr'
> Subject: [Caml-list] Reading a file
>
>
> Hi:
>
> Is there a better way in Ocaml to read a file line by line
> than via the
> read_line function?
>
> I use read_line on a file, perform some tasks on this line
> and store the
> results in a list and after having red the file I use List.rev. The
> problem actually is on big files the function is awfully slow. As
> similar Clean function takes 15 seconds, my Bigloo program takes 25
> second and my C++ programs (via templates) takes 25 secondes but my
> Ocaml program takes 8 minutes.
>
> I am not sure how quick List.rev actually is? In Bigloo
> reversing a list
> has more or less no overhead. My Bigloo function is similar
> to my OCaml
> function. Could it be that OCaml is that slow because I use "try and
> with" constructs in order to check for the end of a file?
>
> Why my Clean function is that fast is incomprehensible for
> me. Does one
> know whether there exists a function in OCaml which converts
> a String to
> a character-list? I use this construct in Clean then in order
> to extract
> floating point numbers from that character list:
> ['1','.','2',...] and
> store this floating point numbers via pattern matching in my
> result-list.
>
> S. Gonzi
>
>
> >
> >
>
>
>
> -------------------
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next prev parent reply other threads:[~2003-05-20 10:21 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ocaml@tagger.yapper.org>
2003-03-31 16:51 ` [Caml-list] How can I check for the use of polymorphic equality? Neel Krishnaswami
2003-03-31 17:33 ` brogoff
2003-04-03 19:44 ` Jason Hickey
2003-04-03 20:40 ` Pierre Weis
2003-04-03 20:53 ` Chris Hecker
2003-04-04 8:46 ` Pierre Weis
2003-04-04 19:05 ` Jason Hickey
2003-04-04 9:10 ` Andreas Rossberg
2003-05-14 11:43 ` [Caml-list] ocaml and large development projects Traudt, Mark
2003-05-14 15:52 ` Jason Hickey
2003-05-18 5:32 ` Chris Hecker
2003-05-18 5:44 ` David Brown
2003-05-18 6:10 ` Chris Hecker
2003-05-18 11:13 ` John Carr
2003-05-18 16:51 ` Ed L Cashin
2003-05-18 18:08 ` Lex Stein
2003-05-18 19:08 ` Ed L Cashin
2003-05-18 19:55 ` Lex Stein
2003-05-19 8:13 ` Markus Mottl
2003-05-19 8:33 ` Nicolas Cannasse
2003-06-02 21:59 ` John Max Skaller
2003-05-18 23:19 ` Chris Hecker
2003-05-18 14:38 ` David Brown
2003-05-18 16:00 ` Ville-Pertti Keinonen
2003-05-19 15:36 ` Brian Hurt
2003-05-19 19:31 ` Chris Hecker
2003-05-19 23:39 ` Seth Kurtzberg
2003-05-20 8:07 ` [Caml-list] ocaml as *.so (was: ...and large development projects) Wolfgang Müller
2003-05-20 8:42 ` [Caml-list] Reading a file Siegfried Gonzi
2003-05-20 10:21 ` Mattias Waldau [this message]
2003-05-20 10:48 ` Nicolas Cannasse
2003-05-20 10:55 ` Markus Mottl
2003-05-20 13:20 ` Michal Moskal
2003-05-20 12:21 ` Siegfried Gonzi
2003-05-21 6:11 ` Siegfried Gonzi
2003-05-21 6:48 ` Siegfried Gonzi
2003-05-21 6:53 ` Siegfried Gonzi
2003-05-21 9:16 ` Markus Mottl
2003-05-21 10:04 ` Eray Ozkural
2003-05-21 16:20 ` brogoff
2003-05-21 8:21 ` Michal Moskal
2003-05-21 7:24 ` [Caml-list] PsiLAB works fine under Linux SuSE 8 Siegfried Gonzi
2003-05-21 9:11 ` [Caml-list] Reading a file Markus Mottl
2003-05-22 6:27 ` Siegfried Gonzi
2003-05-22 10:26 ` Markus Mottl
2003-05-23 5:59 ` Siegfried Gonzi
2003-05-23 6:04 ` Siegfried Gonzi
2003-05-20 10:45 ` [Caml-list] ocaml as *.so (was: ...and large development projects) Nicolas Cannasse
2003-05-20 11:17 ` Wolfgang Müller
2003-05-20 11:31 ` Nicolas Cannasse
2003-05-20 11:40 ` Wolfgang Müller
2003-06-02 22:40 ` John Max Skaller
2003-06-03 13:26 ` [Caml-list] ocaml as *.so Remi Vanicat
2003-06-02 22:42 ` [Caml-list] ocaml and large development projects John Max Skaller
2003-06-02 21:24 ` John Max Skaller
2003-06-02 21:12 ` John Max Skaller
2003-06-03 0:31 ` Chris Hecker
2003-06-03 10:13 ` Michal Moskal
2003-06-03 18:12 ` Chris Hecker
2003-06-03 14:31 ` art yerkes
2003-06-03 21:55 ` Jason Hickey
2003-06-03 22:42 ` Chris Hecker
2003-06-06 23:46 ` John Max Skaller
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