条件を満たす行を取り除く
Posted feedbacks - OCaml
まんまF#でやってみました。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | open System;;
open System.Text;;
open System.IO;;
open Array;;
let fileIO (ifname:string) (ofname:string) =
let streamW = new StreamWriter( ofname, false, Encoding.Default ) in
let streamR = new StreamReader( ifname, Encoding.Default ) in
let rmCommentLn (wstream:StreamWriter) =
let rec readf (rstream:StreamReader) =
let line = rstream.ReadLine() in
if line = null then ()
else
begin
if not (line.StartsWith "#")
then wstream.WriteLine line
else ();
readf rstream
end
in using streamR readf
in using streamW rmCommentLn;;
if (length Sys.argv) = 3
then fileIO Sys.argv.(1) Sys.argv.(2)
else ();;
|
ループを使わずにストリームでやってみました。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | (* 関数合成 *)
let ($) f g x = f (g x)
let _ =
(* ファイルのオープン *)
let input =
open_in "input_file"
in
let output =
open_out "output_file"
in
(* 一行ずつ読み込むストリーム作成 *)
let lines =
Stream.from (fun _ ->
try
Some (input_line input)
with
_ -> None)
in
(* 正規表現で判定する *)
let exp =
Str.regexp "^#"
in
(* 条件にマッチしたら空文字列を返す *)
let filter str =
if Str.string_match exp str 0 then
""
else
str ^ "\n"
in
(* ループでやらずにストリームで処理するところが関数型言語の肝 *)
Stream.iter (output_string output $ filter) lines;
(* 後始末 *)
close_in input;
close_out output
|
再帰関数で書いてみました。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | let rec work (file,str) =
let line =
try
Some (input_line file)
with
_ -> None
in match line with
None -> str
| Some line -> work (file,str^(if ((String.get line 0) = '#') then "" else line^"\n"));;
let in_file = open_in "./hellow.txt";;
let out_file = open_out "./newhellow.txt";;
output_string out_file (work (in_file,""));;
close_in in_file;;
close_out out_file;;
|
改行入りのinput_lineも欲しいなぁ。
1 2 3 4 5 6 7 8 9 10 11 | let rm_line ?(c='#') fname =
let rec loop r w =
try
let l = input_line r ^ "\n" in
if (l.[0] <> c) then (output_string w l);
loop r w
with err ->
close_in r; close_out w;
if err = End_of_file
then Sys.rename (fname^".tmp") fname;
in loop (open_in fname) (open_out (fname^".tmp"));;
|
にしお
#3366()
Rating0/0=0.00
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