File input/output
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Create a file called "output.txt", and place in it the contents of the file "input.txt", via an intermediate variable.
In other words, your program will demonstrate:
- how to read from a file into a variable
- how to write a variable's contents into a file
Oneliners that skip the intermediate variable are of secondary interest — operating systems have copy commands for that.
11l
<lang 11l>V file_contents = File(‘input.txt’).read() File(‘output.txt’, ‘w’).write(file_contents)</lang>
AArch64 Assembly
<lang AArch64 Assembly> /* ARM assembly AARCH64 Raspberry PI 3B */ /* program readwrtFile64.s */
/*******************************************/ /* Constantes file */ /*******************************************/ /* for this file see task include a file in language AArch64 assembly*/ .include "../includeConstantesARM64.inc"
.equ TAILLEBUF, 1000 /*********************************/ /* Initialized data */ /*********************************/ .data szMessErreur: .asciz "Error open input file.\n" szMessErreur4: .asciz "Error open output file.\n" szMessErreur1: .asciz "Error close file.\n" szMessErreur2: .asciz "Error read file.\n" szMessErreur3: .asciz "Error write output file.\n"
/*************************************************/ szMessCodeErr: .asciz "Error code décimal : @ \n"
szNameFileInput: .asciz "input.txt" szNameFileOutput: .asciz "output.txt"
/*******************************************/ /* UnInitialized data */ /*******************************************/ .bss sBuffer: .skip TAILLEBUF sZoneConv: .skip 24 /**********************************************/ /* -- Code section */ /**********************************************/ .text .global main main: // entry of program
mov x0,AT_FDCWD
ldr x1,qAdrszNameFileInput // file name
mov x2,#O_RDWR // flags
mov x3,#0 // mode
mov x8,#OPEN // call system OPEN
svc #0
cmp x0,0 // open error ?
ble erreur
mov x19,x0 // save File Descriptor
ldr x1,qAdrsBuffer // buffer address
mov x2,TAILLEBUF // buffer size
mov x8,READ // call system READ
svc 0
cmp x0,0 // read error ?
ble erreur2
mov x20,x0 // length read characters
// close imput file
mov x0,x19 // Fd
mov x8,CLOSE // call system CLOSE
svc 0
cmp x0,0 // close error ?
blt erreur1
// create output file
mov x0,AT_FDCWD
ldr x1,qAdrszNameFileOutput // file name
mov x2,O_CREAT|O_RDWR // flags
ldr x3,qFicMask1 // Mode
mov x8,OPEN // call system open file
svc 0
cmp x0,#0 // create error ?
ble erreur4
mov x19,x0 // file descriptor
ldr x1,qAdrsBuffer
mov x2,x20 // length to write
mov x8, #WRITE // select system call 'write'
svc #0 // perform the system call
cmp x0,#0 // error write ?
blt erreur3
// close output file
mov x0,x19 // Fd fichier
mov x8, #CLOSE // call system CLOSE
svc #0
cmp x0,#0 // error close ?
blt erreur1
mov x0,#0 // return code OK
b 100f
erreur:
ldr x1,qAdrszMessErreur bl displayError mov x0,#1 // error return code b 100f
erreur1:
ldr x1,qAdrszMessErreur1 bl displayError mov x0,#1 // error return code b 100f
erreur2:
ldr x1,qAdrszMessErreur2 bl displayError mov x0,#1 // error return code b 100f
erreur3:
ldr x1,qAdrszMessErreur3 bl displayError mov x0,#1 // error return code b 100f
erreur4:
ldr x1,qAdrszMessErreur4 bl displayError mov x0,#1 // error return code b 100f
100: // end program
mov x8,EXIT svc 0
qAdrszNameFileInput: .quad szNameFileInput qAdrszNameFileOutput: .quad szNameFileOutput qAdrszMessErreur: .quad szMessErreur qAdrszMessErreur1: .quad szMessErreur1 qAdrszMessErreur2: .quad szMessErreur2 qAdrszMessErreur3: .quad szMessErreur3 qAdrszMessErreur4: .quad szMessErreur4 qAdrsBuffer: .quad sBuffer qFicMask1: .quad 0644 /******************************************************************/ /* display error message */ /******************************************************************/ /* x0 contains error code */ /* x1 contains address error message */ displayError:
stp x2,lr,[sp,-16]! // save registers mov x2,x0 // save error code mov x0,x1 // display message error bl affichageMess mov x0,x2 ldr x1,qAdrsZoneConv // conversion error code bl conversion10S // decimal conversion ldr x0,qAdrszMessCodeErr ldr x1,qAdrsZoneConv bl strInsertAtCharInc // insert result at @ character bl affichageMess // display message final ldp x2,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
qAdrsZoneConv: .quad sZoneConv qAdrszMessCodeErr: .quad szMessCodeErr /********************************************************/ /* File Include fonctions */ /********************************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeARM64.inc"
</lang>
ACL2
<lang lisp>:set-state-ok t
(defun read-channel (channel limit state)
(mv-let (ch state)
(read-char$ channel state)
(if (or (null ch)
(zp limit))
(let ((state (close-input-channel channel state)))
(mv nil state))
(mv-let (so-far state)
(read-channel channel (1- limit) state)
(mv (cons ch so-far) state)))))
(defun read-from-file (filename limit state)
(mv-let (channel state)
(open-input-channel filename :character state)
(mv-let (contents state)
(read-channel channel limit state)
(mv (coerce contents 'string) state))))
(defun write-channel (channel cs state)
(if (endp cs)
(close-output-channel channel state)
(let ((state (write-byte$ (char-code (first cs))
channel state)))
(let ((state (write-channel channel
(rest cs)
state)))
state))))
(defun write-to-file (filename str state)
(mv-let (channel state)
(open-output-channel filename :byte state)
(write-channel channel (coerce str 'list) state)))
(defun copy-file (in out state)
(mv-let (contents state)
(read-from-file in (expt 2 40) state)
(write-to-file out contents state)))</lang>
Ada
Line by line
Assuming everything is fine and no error handling is required, this solution is sufficient: <lang ada>with Ada.Text_IO; use Ada.Text_IO;
procedure Read_And_Write_File_Line_By_Line is
Input, Output : File_Type;
begin
Open (File => Input,
Mode => In_File,
Name => "input.txt");
Create (File => Output,
Mode => Out_File,
Name => "output.txt");
loop
declare
Line : String := Get_Line (Input);
begin
-- You can process the contents of Line here.
Put_Line (Output, Line);
end;
end loop;
Close (Input);
Close (Output);
exception
when End_Error =>
if Is_Open(Input) then
Close (Input);
end if;
if Is_Open(Output) then
Close (Output);
end if;
end Read_And_Write_File_Line_By_Line;</lang>
Expanded with proper error handling and reporting it reads:
<lang ada>with Ada.Command_Line, Ada.Text_IO; use Ada.Command_Line, Ada.Text_IO;
procedure Read_And_Write_File_Line_By_Line is
Read_From : constant String := "input.txt"; Write_To : constant String := "output.txt"; Input, Output : File_Type;
begin
begin
Open (File => Input,
Mode => In_File,
Name => Read_From);
exception
when others =>
Put_Line (Standard_Error,
"Can not open the file '" & Read_From & "'. Does it exist?");
Set_Exit_Status (Failure);
return;
end;
begin
Create (File => Output,
Mode => Out_File,
Name => Write_To);
exception
when others =>
Put_Line (Standard_Error,
"Can not create a file named '" & Write_To & "'.");
Set_Exit_Status (Failure);
return;
end;
loop
declare
Line : String := Get_Line (Input);
begin
-- You can process the contents of Line here.
Put_Line (Output, Line);
end;
end loop;
Close (Input);
Close (Output);
exception
when End_Error =>
if Is_Open(Input) then
Close (Input);
end if;
if Is_Open(Output) then
Close (Output);
end if;
end Read_And_Write_File_Line_By_Line;</lang>
Character by character
The following example reads and writes each file one character at a time. (You should of course add error reporting as in the example above.) <lang ada>with Ada.Sequential_IO;
procedure Read_And_Write_File_Character_By_Character is
package Char_IO is new Ada.Sequential_IO (Character); use Char_IO;
Input, Output : File_Type; Buffer : Character;
begin
Open (File => Input, Mode => In_File, Name => "input.txt");
Create (File => Output, Mode => Out_File, Name => "output.txt");
loop
Read (File => Input, Item => Buffer);
Write (File => Output, Item => Buffer);
end loop;
Close (Input);
Close (Output);
exception
when End_Error =>
if Is_Open(Input) then
Close (Input);
end if;
if Is_Open(Output) then
Close (Output);
end if;
end Read_And_Write_File_Character_By_Character;</lang>
Using Ada.Text_IO.Text_Streams
The following solution uses stream I/O. Any file of Ada.Text_IO can be used to obtain a corresponding stream. Reading and writing streams is more efficient than reading text files directly, because it skips formatting.
<lang ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Text_IO.Text_Streams; use Ada.Text_IO.Text_Streams;
procedure Using_Text_Streams is
Input, Output : File_Type; Buffer : Character;
begin
Open (File => Input, Mode => In_File, Name => "input.txt");
Create (File => Output, Mode => Out_File, Name => "output.txt");
loop
Buffer := Character'Input (Stream (Input));
Character'Write (Stream (Output), Buffer);
end loop;
Close (Input);
Close (Output);
exception
when End_Error =>
if Is_Open(Input) then
Close (Input);
end if;
if Is_Open(Output) then
Close (Output);
end if;
end Using_Text_Streams;</lang>
Aime
<lang aime>file i, o; text s;
i.open("input.txt", OPEN_READONLY, 0); o.open("output.txt", OPEN_CREATE | OPEN_TRUNCATE | OPEN_WRITEONLY,
0644);
while (i.line(s) ^ -1) {
o.text(s);
o.byte('\n');
}</lang>
ALGOL 68
<lang algol68>PROC copy file v1 = (STRING in name, out name)VOID: (
# note: algol68toc-1.18 - can compile, but not run v1 # INT errno; FILE in file, out file; errno := open(in file, in name, stand in channel); errno := open(out file, out name, stand out channel);
BOOL in ended := FALSE; PROC call back ended = (REF FILE f) BOOL: in ended := TRUE; on logical file end(in file, call back ended);
STRING line; WHILE get(in file, (line, new line));
- WHILE # NOT in ended DO # break to avoid excess new line #
put(out file, (line, new line)) OD;
ended:
close(in file); close(out file)
);
PROC copy file v2 = (STRING in name, out name)VOID: (
INT errno; FILE in file, out file; errno := open(in file, in name, stand in channel); errno := open(out file, out name, stand out channel);
PROC call back ended = (REF FILE f) BOOL: GO TO done; on logical file end(in file, call back ended);
STRING line; DO get(in file, line); put(out file, line); get(in file, new line); put(out file, new line) OD;
done:
close(in file); close(out file)
);
test:(
copy file v2("input.txt","output.txt")
)</lang>
AppleScript
<lang applescript>on copyFile from src into dst
set filedata to read file src
set outfile to open for access dst with write permission
write filedata to outfile
close access outfile
end copyFile
copyFile from ":input.txt" into ":output.txt"</lang>
ARM Assembly
<lang ARM Assembly>
/* ARM assembly Raspberry PI */ /* program readwrtfile.s */
/*********************************************/ /*constantes */ /********************************************/ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ READ, 3 .equ WRITE, 4 .equ OPEN, 5 .equ CLOSE, 6 .equ CREATE, 8 /* file */ .equ O_RDWR, 0x0002 @ open for reading and writing
.equ TAILLEBUF, 1000 /*********************************/ /* Initialized data */ /*********************************/ .data szMessErreur: .asciz "Erreur ouverture fichier input.\n" szMessErreur4: .asciz "Erreur création fichier output.\n" szMessErreur1: .asciz "Erreur fermeture fichier.\n" szMessErreur2: .asciz "Erreur lecture fichier.\n" szMessErreur3: .asciz "Erreur d'écriture dans fichier de sortie.\n" szRetourligne: .asciz "\n" szMessErr: .ascii "Error code : " sDeci: .space 15,' '
.asciz "\n"
szNameFileInput: .asciz "input.txt" szNameFileOutput: .asciz "output.txt"
/*******************************************/ /* DONNEES NON INITIALISEES */ /*******************************************/ .bss sBuffer: .skip TAILLEBUF
/**********************************************/ /* -- Code section */ /**********************************************/ .text .global main main:
push {fp,lr} /* save registers */
ldr r0,iAdrszNameFileInput @ file name mov r1,#O_RDWR @ flags mov r2,#0 @ mode mov r7,#OPEN @ call system OPEN swi #0 cmp r0,#0 @ open error ? ble erreur mov r8,r0 @ save File Descriptor ldr r1,iAdrsBuffer @ buffer address mov r2,#TAILLEBUF @ buffer size mov r7, #READ @ call system READ swi 0 cmp r0,#0 @ read error ? ble erreur2 mov r2,r0 @ length read characters
/* close imput file */ mov r0,r8 @ Fd mov r7, #CLOSE @ call system CLOSE swi 0 cmp r0,#0 @ close error ? blt erreur1
@ create output file ldr r0,iAdrszNameFileOutput @ file name ldr r1,iFicMask1 @ flags mov r7, #CREATE @ call system create file swi 0 cmp r0,#0 @ create error ? ble erreur4 mov r0,r8 @ file descriptor ldr r1,iAdrsBuffer @ et r2 contains the length to write mov r7, #WRITE @ select system call 'write' swi #0 @ perform the system call cmp r0,#0 @ error write ? blt erreur3
@ close output file mov r0,r8 @ Fd fichier mov r7, #CLOSE @ call system CLOSE swi #0 cmp r0,#0 @ error close ? blt erreur1 mov r0,#0 @ return code OK b 100f
erreur:
ldr r1,iAdrszMessErreur bl afficheerreur mov r0,#1 @ error return code b 100f
erreur1:
ldr r1,iAdrszMessErreur1 bl afficheerreur mov r0,#1 @ error return code b 100f
erreur2:
ldr r1,iAdrszMessErreur2 bl afficheerreur mov r0,#1 @ error return code b 100f
erreur3:
ldr r1,iAdrszMessErreur3 bl afficheerreur mov r0,#1 @ error return code b 100f
erreur4:
ldr r1,iAdrszMessErreur4 bl afficheerreur mov r0,#1 @ error return code b 100f
100: @ end program
pop {fp,lr} /* restaur des 2 registres */
mov r7, #EXIT /* appel fonction systeme pour terminer */
swi 0
iAdrszNameFileInput: .int szNameFileInput iAdrszNameFileOutput: .int szNameFileOutput iAdrszMessErreur: .int szMessErreur iAdrszMessErreur1: .int szMessErreur1 iAdrszMessErreur2: .int szMessErreur2 iAdrszMessErreur3: .int szMessErreur3 iAdrszMessErreur4: .int szMessErreur4 iAdrsBuffer: .int sBuffer iFicMask1: .octa 0644 /******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess:
push {r0,r1,r2,r7,lr} /* save registres */
mov r2,#0 /* counter length */
1: /* loop length calculation */
ldrb r1,[r0,r2] /* read octet start position + index */
cmp r1,#0 /* if 0 its over */
addne r2,r2,#1 /* else add 1 in the length */
bne 1b /* and loop */
/* so here r2 contains the length of the message */
mov r1,r0 /* address message in r1 */
mov r0,#STDOUT /* code to write to the standard output Linux */
mov r7, #WRITE /* code call system "write" */
swi #0 /* call systeme */
pop {r0,r1,r2,r7,lr} /* restaur des 2 registres */
bx lr /* return */
/***************************************************/ /* display error message */ /***************************************************/ /* r0 contains error code r1 address error message */ afficheerreur:
push {r1-r2,lr} @ save registers
mov r2,r0 @ save error code
mov r0,r1 @ address error message
bl affichageMess @ display error message
mov r0,r2 @ error code
ldr r1,iAdrsDeci @ result address
bl conversion10S
ldr r0,iAdrszMessErr @ display error code
bl affichageMess
pop {r1-r2,lr} @ restaur registers
bx lr @ return function
iAdrszMessErr: .int szMessErr iAdrsDeci: .int sDeci
/***************************************************/ /* Converting a register to a signed decimal */ /***************************************************/ /* r0 contains value and r1 area address */ conversion10S:
push {r0-r4,lr} @ save registers
mov r2,r1 /* debut zone stockage */
mov r3,#'+' /* par defaut le signe est + */
cmp r0,#0 @ negative number ?
movlt r3,#'-' @ yes
mvnlt r0,r0 @ number inversion
addlt r0,#1
mov r4,#10 @ length area
1: @ start loop
bl divisionPar10R add r1,#48 @ digit strb r1,[r2,r4] @ store digit on area sub r4,r4,#1 @ previous position cmp r0,#0 @ stop if quotient = 0 bne 1b
strb r3,[r2,r4] @ store signe subs r4,r4,#1 @ previous position blt 100f @ if r4 < 0 -> end
mov r1,#' ' @ space
2:
strb r1,[r2,r4] @store byte space subs r4,r4,#1 @ previous position bge 2b @ loop if r4 > 0
100:
pop {r0-r4,lr} @ restaur registers
bx lr
/***************************************************/ /* division for 10 fast unsigned */ /***************************************************/ @ r0 contient le dividende @ r0 retourne le quotient @ r1 retourne le reste divisionPar10R:
push {r2,lr} @ save registers
sub r1, r0, #10 @ calcul de r0 - 10
sub r0, r0, r0, lsr #2 @ calcul de r0 - (r0 /4)
add r0, r0, r0, lsr #4 @ calcul de (r0-(r0/4))+ ((r0-(r0/4))/16
add r0, r0, r0, lsr #8 @ etc ...
add r0, r0, r0, lsr #16
mov r0, r0, lsr #3
add r2, r0, r0, asl #2
subs r1, r1, r2, asl #1 @ calcul (N-10) - (N/10)*10
addpl r0, r0, #1 @ regul quotient
addmi r1, r1, #10 @ regul reste
pop {r2,lr}
bx lr
</lang>
Arturo
<lang arturo>source: [read "input.txt"] write "output.txt" source
print source</lang>
- Output:
This is some sample text in input.txt
AutoHotkey
Method 1: the input file can be processed line by line. <lang AutoHotkey>Loop, Read, input.txt, output.txt
FileAppend, %A_LoopReadLine%`n</lang>
Method 2: the input file can be read at once if it is less than 1 GB. <lang autohotkey>FileRead, var, input.txt FileAppend, %var%, output.txt</lang> Method 3: the file can be copied without I/O. <lang autohotkey>FileCopy, input.txt, output.txt</lang>
Binary I/O is possible with this library from Laszlo.
AWK
(This does not handle properly binary files)
<lang awk>BEGIN {
while ( (getline <"input.txt") > 0 ) {
print >"output.txt"
}
}</lang>
Babel
<lang babel>(main
{ "input.txt" >>> -- File is now on stack
foo set -- File is now in 'foo'
foo "output.txt" <<< })</lang>
The spirit of Babel is to manipulate things on the stack whenever feasible. In this example, I showed how to save it into a symbolic variable (foo) but this step would not be necessary for many simple file-processing tasks, such as splitting on newlines or spaces.
Also note that the >>> (slurp) and <<< (spit) operators only handle "small" files - the limit is configurable but the default limit is 100MB. If you want to open very large files or if you need to perform a lot of interactive file I/O, Babel provides operators that wrap the C standard library fopen()/fclose() functions.
BASIC
<lang qbasic> OPEN "INPUT.TXT" FOR INPUT AS #1
OPEN "OUTPUT.TXT" FOR OUTPUT AS #2 DO UNTIL EOF(1) LINE INPUT #1, Data$ PRINT #2, Data$ LOOP CLOSE #1 CLOSE #2 SYSTEM</lang>
Applesoft BASIC
This is only meant to copy a sequential text file. It is very unlikely that this works copying a random access text file. <lang ApplesoftBasic>100 I$ = "INPUT.TXT" 110 O$ = "OUTPUT.TXT" 120 M$ = CHR$(13) 130 D$ = CHR$(4) 140 PRINT D$"VERIFY"I$ 150 PRINT D$"OPEN"O$ 160 PRINT D$"DELETE"O$ 170 PRINT D$"OPEN"O$ 180 PRINT D$"OPEN"I$
190 PRINT D$"READ"I$ 200 ONERR GOTO 280 210 GET C$ 220 POKE 216,0 230 PRINT M$D$"WRITE"O$",B"B 240 B = B + 1 250 P = 2 - (C$ <> M$) 260 PRINT MID$(C$, P) 270 GOTO 190
280 POKE 216,0 290 EOF = PEEK(222) = 5 300 IF NOT EOF THEN RESUME 310 PRINT M$D$"CLOSE" </lang>
Commodore BASIC
<lang commodorebasic>10 print chr$(14) : rem switch to upper+lower case set 20 print "read seq file input.txt and write to seq file output.txt" 30 open 4,8,4,"input.txt,seq,read" 40 open 8,8,8,"@:output.txt,seq,write" : rem '@'== new file 50 for i=0 to 1 : rem while i==0 60 input#4,a$ 70 i=64 and st : rem check bit 6=='end of file' 80 print a$ 90 print#8,a$ 100 next : rem end while 110 close 4 120 close 8 130 end</lang>
IS-BASIC
<lang IS-BASIC>100 STRING TX$*254 110 OPEN #1:"output.txt" 120 OPEN #2:"input.txt" ACCESS OUTPUT 130 WHEN EXCEPTION USE IOERROR 140 DO 150 LINE INPUT #1:TX$ 160 PRINT #2:TX$ 170 LOOP 180 END WHEN 190 HANDLER IOERROR 200 IF EXTYPE<>8001 THEN PRINT EXSTRING$(EXTYPE) 210 CLOSE #1 220 CLOSE #2 230 END HANDLER</lang>
Batch File
<lang dos>copy input.txt output.txt</lang> or <lang dos>type input.txt > output.txt</lang> or <lang dos>for /f "" %L in ('more^<input.txt') do echo %L>>output.txt</lang>
There may be other techniques too.
BBC BASIC
BBC BASIC for Windows has a file copy command: <lang bbcbasic>*COPY input.txt output.txt</lang> Alternatively the copy can be done explicitly: <lang bbcbasic>infile% = OPENIN("input.txt") outfile% = OPENOUT("output.txt") WHILE NOT EOF#infile%
BPUT #outfile%, BGET#infile%
ENDWHILE CLOSE #infile% CLOSE #outfile%</lang>
Befunge
<lang befunge>0110"txt.tupni"#@i10"txt.tuptuo"#@o@</lang>
This linear program tries to open "input.txt" as text file (or aborts). It then writes the content in text mode (i.e. minus trailing spaces) to "output.txt" (or aborts).
Bracmat
<lang bracmat>put$(get$"input.txt","output.txt",NEW)</lang>
C
<lang c>#include <stdio.h>
int main(int argc, char **argv) {
FILE *in, *out; int c;
in = fopen("input.txt", "r");
if (!in) {
fprintf(stderr, "Error opening input.txt for reading.\n");
return 1;
}
out = fopen("output.txt", "w");
if (!out) {
fprintf(stderr, "Error opening output.txt for writing.\n");
fclose(in);
return 1;
}
while ((c = fgetc(in)) != EOF) {
fputc(c, out);
}
fclose(out); fclose(in); return 0;
}</lang>
A couple of remarks on the preceding example:
It uses fgetc to read one character at a time. Each character is visited, even though there's nothing to do with it. Copying bigger blocks of data is much more efficient.
The following example addresses those issues. To avoid buffered I/O, it uses open(), read(), write() and close(), which are part of POSIX.
<lang c>#include <unistd.h>
- include <fcntl.h>
- include <sys/types.h>
- include <sys/stat.h>
/* we just return a yes/no status; caller can check errno */ int copy_file(const char *in, const char *out) { int ret = 0; int fin, fout; ssize_t len; char *buf[4096]; /* buffer size, some multiple of block size preferred */ struct stat st;
if ((fin = open(in, O_RDONLY)) == -1) return 0; if (fstat(fin, &st)) goto bail;
/* open output with same permission */ fout = open(out, O_WRONLY|O_CREAT|O_TRUNC, st.st_mode & 0777); if (fout == -1) goto bail;
while ((len = read(fin, buf, 4096)) > 0) write(fout, buf, len);
ret = len ? 0 : 1; /* last read should be 0 */
bail: if (fin != -1) close(fin); if (fout != -1) close(fout); return ret; }
int main() { copy_file("infile", "outfile"); return 0; }</lang>
If it's certain that mapping the whole input file into memory poses no problem (there can be all kinds of problems), this may be the most efficient:<lang c>int copy_file(const char *in, const char *out) { int ret = 0; int fin, fout; char *bi; struct stat st;
if ((fin = open(in, O_RDONLY)) == -1) return 0; if (fstat(fin, &st)) goto bail;
fout = open(out, O_WRONLY|O_CREAT|O_TRUNC, st.st_mode & 0777); if (fout == -1) goto bail;
bi = mmap(0, st.st_size, PROT_READ, MAP_PRIVATE, fin, 0);
ret = (bi == (void*)-1) ? 0 : (write(fout, bi, st.st_size) == st.st_size);
bail: if (fin != -1) close(fin); if (fout != -1) close(fout); if (bi != (void*)-1) munmap(bi, st.st_size); return ret; }</lang>
C#
The long way:
<lang csharp>using System.IO;
using (var reader = new StreamReader("input.txt")) using (var writer = new StreamWriter("output.txt")) {
var text = reader.ReadToEnd(); writer.Write(text);
}</lang>
The short way:
<lang csharp>using System.IO;
var text = File.ReadAllText("input.txt"); File.WriteAllText("output.txt", text);</lang>
C++
<lang cpp>#include <iostream>
- include <fstream>
- include <string>
using namespace std;
int main() {
string line;
ifstream input ( "input.txt" );
ofstream output ("output.txt");
if (output.is_open()) {
if (input.is_open()){
while (getline (input,line)) {
output << line << endl;
}
input.close(); // Not necessary - will be closed when variable goes out of scope.
}
else {
cout << "input.txt cannot be opened!\n";
}
output.close(); // Not necessary - will be closed when variable goes out of scope.
}
else {
cout << "output.txt cannot be written to!\n";
}
return 0;
}</lang>
Simpler version:
<lang cpp>#include <iostream>
- include <fstream>
- include <cstdlib>
int main() {
std::ifstream input("input.txt");
if (!input.is_open())
{
std::cerr << "could not open input.txt for reading.\n";
return EXIT_FAILURE;
}
std::ofstream output("output.txt");
if (!output.is_open())
{
std::cerr << "could not open output.txt for writing.\n";
return EXIT_FAILURE;
}
output << input.rdbuf();
if (!output)
{
std::cerr << "error copying the data.\n";
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}</lang>
Using istream- and ostream- iterators:
<lang cpp># include <algorithm>
- include <fstream>
int main() {
std::ifstream ifile("input.txt");
std::ofstream ofile("output.txt");
std::copy(std::istreambuf_iterator<char>(ifile),
std::istreambuf_iterator<char>(),
std::ostreambuf_iterator<char>(ofile));
}</lang>
Even simpler way:
<lang cpp>#include <fstream>
int main() {
std::ifstream input("input.txt");
std::ofstream output("output.txt");
output << input.rdbuf();
}</lang>
Clean
Define a function that copies the content from one file to another.
<lang clean>import StdEnv
copyFile fromPath toPath world
# (ok, fromFile, world) = fopen fromPath FReadData world
| not ok = abort ("Cannot open " +++ fromPath +++ " for reading")
# (ok, toFile, world) = fopen toPath FWriteData world
| not ok = abort ("Cannot open " +++ toPath +++ " for writing")
# (fromFile, toFile) = copyData 1024 fromFile toFile
# (ok, world) = fclose fromFile world
| not ok = abort ("Cannot close " +++ fromPath +++ " after reading")
# (ok, world) = fclose toFile world
| not ok = abort ("Cannot close " +++ toPath +++ " after writing")
= world
where
copyData bufferSize fromFile toFile
# (buffer, fromFile) = freads fromFile bufferSize
# toFile = fwrites buffer toFile
| size buffer < bufferSize = (fromFile, toFile) // we're done
= copyData bufferSize fromFile toFile // continue recursively</lang>
Apply this function to the world to copy a file.
<lang clean>Start world = copyFile "input.txt" "output.txt" world</lang>
Clojure
<lang lisp> (use 'clojure.java.io)
(copy (file "input.txt") (file "output.txt")) </lang>
<lang lisp>
- simple file writing
(spit "filename.txt" "your content here")
- simple file reading
(slurp "filename.txt") </lang>
COBOL
COBOL 85
Flags used for Micro Focus COBOL:
$set ans85 flag"ans85" flagas"s" sequential"line"
<lang COBOL> identification division.
program-id. copyfile.
environment division.
input-output section.
file-control.
select input-file assign to "input.txt"
organization sequential
.
select output-file assign to "output.txt"
organization sequential
.
data division.
file section.
fd input-file.
1 input-record pic x(80).
fd output-file.
1 output-record pic x(80).
working-storage section.
1 end-of-file-flag pic 9 value 0.
88 eof value 1.
1 text-line pic x(80).
procedure division.
begin.
open input input-file
output output-file
perform read-input
perform until eof
write output-record from text-line
perform read-input
end-perform
close input-file output-file
stop run
.
read-input.
read input-file into text-line
at end
set eof to true
end-read
.
end program copyfile. </lang>
Implementation
<lang cobol> IDENTIFICATION DIVISION.
PROGRAM-ID. file-io.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT in-file ASSIGN "input.txt"
ORGANIZATION LINE SEQUENTIAL.
SELECT OPTIONAL out-file ASSIGN "output.txt"
ORGANIZATION LINE SEQUENTIAL.
DATA DIVISION.
FILE SECTION.
FD in-file.
01 in-line PIC X(256).
FD out-file.
01 out-line PIC X(256).
PROCEDURE DIVISION.
DECLARATIVES.
in-file-error SECTION.
USE AFTER ERROR ON in-file.
DISPLAY "An error occurred while using input.txt."
GOBACK
.
out-file-error SECTION.
USE AFTER ERROR ON out-file.
DISPLAY "An error occurred while using output.txt."
GOBACK
.
END DECLARATIVES.
mainline.
OPEN INPUT in-file
OPEN OUTPUT out-file
PERFORM FOREVER
READ in-file
AT END
EXIT PERFORM
END-READ
WRITE out-line FROM in-line
END-PERFORM
CLOSE in-file, out-file
.</lang>
Built-in Subroutines
<lang cobol>*> Originally from ACUCOBOL-GT CALL "C$COPY" USING "input.txt", "output.txt", 0</lang> <lang cobol>*> Originally from Micro Focus COBOL CALL "CBL_COPY_FILE" USING "input.txt", "output.txt"</lang>
ColdFusion
<lang cfm><cfif fileExists(expandPath("input.txt"))>
<cffile action="read" file="#expandPath('input.txt')#" variable="inputContents">
<cffile action="write" file="#expandPath('output.txt')#" output="#inputContents#">
</cfif></lang>
Common Lisp
By lines:
<lang lisp>(with-open-file (in #p"input.txt" :direction :input)
(with-open-file (out #p"output.txt" :direction :output)
(loop for line = (read-line in nil 'foo)
until (eq line 'foo)
do (write-line line out))))</lang>
By arbitrary blocks and for possibly-binary files:
<lang lisp>(defconstant +buffer-size+ (expt 2 16))
(with-open-file (in #p"input.txt" :direction :input
:element-type '(unsigned-byte 8))
(with-open-file (out #p"output.txt"
:direction :output
:element-type (stream-element-type in))
(loop with buffer = (make-array +buffer-size+
:element-type (stream-element-type in))
for size = (read-sequence buffer in)
while (plusp size)
do (write-sequence buffer out :end size))))</lang>
If you're on an odd platform which actually stores text/binary/... type information for files and your CL implementation will use this information, then in should be opened with :element-type :default.
D
<lang d>import std.file: copy;
void main() {
copy("input.txt", "output.txt");
}</lang>
very plainly, with an intermediate variable: <lang d> void main() { import std.file; auto data = std.file.read("input.txt"); std.file.write("output.txt", data); } </lang>
via an intermediate buffer variable: <lang d>import std.stdio;
int main() {
auto from = File("input.txt", "rb");
scope(exit) from.close();
auto to = File("output.txt", "wb");
scope(exit) to.close();
foreach(buffer; from.byChunk(new ubyte[4096*1024])) {
to.rawWrite(buffer);
}
return 0;
}</lang>
Copy the content from one file to another (exceptions are handled by Tango): <lang d>import tango.io.device.File;
void main() {
auto from = new File("input.txt");
auto to = new File("output.txt", File.WriteCreate);
to.copy(from).close;
from.close;
}</lang> Or a shorter example without explicitly closing the output file: <lang d>import tango.io.device.File;
void main() {
auto to = new File("output.txt", File.WriteCreate);
to.copy(new File("input.txt")).close;
}</lang>
DCL
<lang DCL>$ open input input.txt $ open /write output output.txt $ loop: $ read /end_of_file = done input line $ write output line $ goto loop $ done: $ close input $ close output</lang>
Delphi
Delphi supports both typed and untyped as well as a textfile type for files. Delphi provides a default 128 byte buffer for text files. This may be enlarged via a call to SetTextBuff(Var F: Text; Var Buf [Size : integer]) procedure. All other files have no buffer at all and it is the programmers option to do buffering.
The following file I/O procedures have existed since Turbo Pascal V-3.
- Read(F,V1..Vn) - ReadLn(F,V1..Vn) - Write(F,V1[,V2..Vn]) - WriteLn(f,V1[,V2..Vn]) - BlockRead(F,Buff,BytesToRead[,BytesRead]) - BlockWrite(F,Buff,BytesToRead[,BytesWritten])
Files are opened using:
AssignFile(f,{fully qualified path and file name})
Assigns the file name to the file structure in preparation for opening.
Reset(f)
Opens and existing file. If it does not exist EIOError is raised.
Rewrite(f)
Creates a new file and opens it for I/O. If the files exists is is overwritten.
Delphi implemented Streams of which a variant is TFileStream and are very closely related to the Windows API for file handling.
- Text File I/O -
<lang delphi>var
f : TextFile ; s : string ;
begin
AssignFile(f,[fully qualified file name); Reset(f); writeln(f,s); Reset(f); ReadLn(F,S); CloseFile(
end;</lang>
- Untyped File I/O -
This is perhaps one of the most powerful I/O functions built into Pascal. This will allow you to open and read a file of ANY type, regardless of structure, size or content. Note the usage of Reset(). This is using the optional size parameter that instructs the record size of file I/O. This could have been called with SizeOf(Buff) as the optional parameter but that would have limited flexibility. Calling it with a size of ONE byte allows you to adjust the buffer size on the fly, as conditions warrant. Also note the use of the BytesRead parameter. When included in the BlockRead() function it will return the number of bytes actually read. If this is not included, then if your directive to read n bytes is greater then the size of the file, the EOF will be encountered unexpectedly and EIOError will be raised.
<lang delphi>var
f : File ; buff : array[1.1024] of byte ; BytesRead : Integer ;
begin
AssignFile(f,fully qualified file name); Reset(f,1); Blockread(f,Buff,SizeOf(Buff),BytesRead); CloseFile(f);
end;</lang>
- Typed File I/O -
Typed file I/O is very useful when reading and writing structures. An Address List is quiet easy to write when using this type of I/O. The same file procedures are used with some subtle differences. Bite below in the blockread and blockwrite procedures that the bytes to read or write are 1. Also note that the reset procedure is not called with a buffer size. When performing Typed File I/O the size of the type definition is the buffer size. In the BlockRead() and BlockWrite() procedures I elected to read one record. Had I declared a very large buffer of type tAddressBook of say 500 records, I could have set bytes to read as SizeOf(Buffer) thereby reading a minimum of 500 records.
<lang delphi>type
tAddressBook = Record
FName : string[20];
LName : string[30];
Address : string[30];
City : string[30];
State : string[2];
Zip5 : string[5];
Zip4 : string[4];
Phone : string[14];
Deleted : boolean ;
end;
var
f : file of tAddressBook ; v : tAddressBook ; bytes : integer ;
begin
AssignFile(f,fully qualified file name); Reset(f); Blockread(f,V,1,Bytes); Edit(v); Seek(F,FilePos(f)-1); BlockWrite(f,v,1,bytes); CloseFile(f);
end;</lang>
DIBOL-11
<lang DIBOL-11>
START ;Simple File Input and Output
RECORD TEMP
INLINE, A72
PROC
OPEN (8,I,"input.txt")
OPEN (9,O,"output.txt")
LOOP,
READS(8,TEMP,END)
WRITES(9,TEMP)
GOTO LOOP
END,
CLOSE 8
CLOSE 9
END
</lang>
E
<lang e><file:output.txt>.setText(<file:input.txt>.getText())</lang>
(This version holds the entire contents in memory.)
Eiffel
<lang eiffel >class
APPLICATION
create
make
feature {NONE} -- Initialization
make
-- Run application.
do
create input_file.make_open_read ("input.txt")
create output_file.make_open_write ("output.txt")
from
input_file.read_character
until
input_file.exhausted
loop
output_file.put (input_file.last_character)
input_file.read_character
end
input_file.close
output_file.close
end
feature -- Access
input_file: PLAIN_TEXT_FILE output_file: PLAIN_TEXT_FILE
end</lang>
Elena
ELENA 4.x : <lang elena>import system'io;
public program() {
var text := File.assign("input.txt").readContent();
File.assign("output.txt").saveContent(text);
}</lang>
Elixir
Read in the whole file and write the contents to a new file. <lang Elixir>defmodule FileReadWrite do
def copy(path,new_path) do
case File.read(path) do
# In case of success, write to the new file
{:ok, body} ->
# Can replace with :write! to generate an error upon failure
File.write(new_path,body)
# If not successful, raise an error
{:error,reason} ->
# Using Erlang's format_error to generate error string
:file.format_error(reason)
end
end
end
FileReadWrite.copy("input.txt","output.txt")</lang>
Built in function: <lang Elixir>File.cp!("input.txt", "output.txt")</lang>
Erlang
<lang erlang> -module( file_io ).
-export( [task/0] ).
task() ->
{ok, Contents} = file:read_file( "input.txt" ),
ok = file:write_file( "output.txt", Contents ).
</lang>
Euphoria
Read the entire file and then write it
<lang euphoria>include std/io.e write_lines("output.txt", read_lines("input.txt"))</lang>
Line-by-line reading and writing
<lang euphoria>integer in,out object line
in = open("input.txt","r") out = open("output.txt","w")
while 1 do
line = gets(in)
if atom(line) then -- EOF reached
exit
end if
puts(out,line)
end while
close(out) close(in)</lang>
F#
Using an intermediate variable for the input file content is not ideomatic in functional programming. Nevertheless...
<lang fsharp>open System.IO
let copyFile fromTextFileName toTextFileName =
let inputContent = File.ReadAllText fromTextFileName inputContent |> fun text -> File.WriteAllText(toTextFileName, text)
[<EntryPoint>] let main argv =
copyFile "input.txt" "output.txt" 0
</lang>
Factor
Holds entire file content in memory: <lang factor>"input.txt" binary file-contents "output.txt" binary set-file-contents</lang> A bit longer, but only holds a small amount of data in memory. If opening the file for writing fails, we want to clean up the file that's open for reading: <lang factor>[
"input.txt" binary <file-reader> &dispose "output.txt" binary <file-writer> stream-copy
] with-destructors </lang> Possibly cheating: <lang factor>"input.txt" "output.txt" copy-file</lang>
Forth
Forth traditionally has not had any file handling capabilities, preferring instead to operate on a disk image block by block. Most modern Forth systems however run under an existing operating system and provide methods for disk access.
<lang forth>\ <to> <from> copy-file
- copy-file ( a1 n1 a2 n2 -- )
r/o open-file throw >r
w/o create-file throw r>
begin
pad maxstring 2 pick read-file throw
?dup while
pad swap 3 pick write-file throw
repeat
close-file throw
close-file throw ;
\ Invoke it like this: s" output.txt" s" input.txt" copy-file</lang>
Note the use of "2 pick" to get the input file handle and "3 pick" to get the output file handle. Local or global variables could have been used, but in this implementation simple stack manipulation was chosen. Also, only maxstring bytes are copied at a time, and the global "pad" memory area is used to hold the data. For faster copies, allocating a larger buffer could be advantageous.
Also, abort" can be used instead of throw if desired.
A good practice is to ask the user the file name he wants to create like in this short example <lang>: INPUT$ ( text -- n n )
pad swap accept pad swap ;
cr ." Enter file name : " 20 INPUT$ w/o create-file throw Value fd-out
- get-content cr ." Enter your nickname : " 20 INPUT$ fd-out write-file cr ;
- close-output ( -- ) fd-out close-file throw ;
get-content \ Inject a carriage return at end of file s\" \n" fd-out write-file close-output bye</lang>
Fortran
It uses the access="stream" which is defined in Fortran 2003 standard and should allow to "copy" also binary data easily.
<lang fortran>program FileIO
integer, parameter :: out = 123, in = 124 integer :: err character :: c
open(out, file="output.txt", status="new", action="write", access="stream", iostat=err)
if (err == 0) then
open(in, file="input.txt", status="old", action="read", access="stream", iostat=err)
if (err == 0) then
err = 0
do while (err == 0)
read(unit=in, iostat=err) c
if (err == 0) write(out) c
end do
close(in)
end if
close(out)
end if
end program FileIO</lang>
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
/' input.txt contains:
The quick brown fox jumps over the lazy dog. Empty vessels make most noise. Too many chefs spoil the broth. A rolling stone gathers no moss. '/
Open "output.txt" For Output As #1 Open "input.txt" For Input As #2 Dim line_ As String ' note that line is a keyword
While Not Eof(2)
Line Input #2, line_ Print #1, line_
Wend
Close #2 Close #1</lang>
- Output:
output.txt contains: The quick brown fox jumps over the lazy dog. Empty vessels make most noise. Too many chefs spoil the broth. A rolling stone gathers no moss.
Frink
<lang frink> contents = read["file:input.txt"] w = new Writer["output.txt"] w.print[contents] w.close[] </lang>
Gambas
<lang gambas>Public Sub Main() Dim sOutput As String = "Hello " Dim sInput As String = File.Load(User.Home &/ "input.txt") 'Has the word 'World!' stored
File.Save(User.Home &/ "output.txt", sOutput) File.Save(User.Home &/ "input.txt", sOutput & sInput)
Print "'input.txt' contains - " & sOutput & sInput Print "'output.txt' contains - " & sOutput
End</lang> Output:
'input.txt' contains - Hello World! 'output.txt' contains - Hello
GAP
<lang gap>CopyFile := function(src, dst)
local f, g, line;
f := InputTextFile(src);
g := OutputTextFile(dst, false);
while true do
line := ReadLine(f);
if line = fail then
break
else
WriteLine(g, Chomp(line));
fi;
od;
CloseStream(f);
CloseStream(g);
end;</lang>
GML
<lang GML>var file, str; file = file_text_open_read("input.txt"); str = ""; while (!file_text_eof(file))
{
str += file_text_read_string(file);
if (!file_text_eof(file))
{
str += "
"; //It is important to note that a linebreak is actually inserted here rather than a character code of some kind
file_text_readln(file);
}
}
file_text_close(file);
file = file_text_open_write("output.txt"); file_text_write_string(file,str); file_text_close(file);</lang>
Go
<lang go>package main
import (
"fmt" "io/ioutil"
)
func main() {
b, err := ioutil.ReadFile("input.txt")
if err != nil {
fmt.Println(err)
return
}
if err = ioutil.WriteFile("output.txt", b, 0666); err != nil {
fmt.Println(err)
}
}</lang> Alternative solution is not a one-liner, but is one of "secondary interest" that copies data from one file to another without an intermediate variable. <lang go>package main
import (
"io" "log" "os"
)
func CopyFile(out, in string) (err error) {
var inf, outf *os.File
inf, err = os.Open(in)
if err != nil {
return
}
defer func() {
cErr := inf.Close()
if err == nil {
err = cErr
}
}()
outf, err = os.Create(out)
if err != nil {
return
}
_, err = io.Copy(outf, inf)
cErr := outf.Close()
if err == nil {
err = cErr
}
return
}
func main() {
if err := CopyFile("output.txt", "input.txt"); err != nil {
log.Fatal(err)
}
}</lang>
Groovy
Using File <lang groovy>content = new File('input.txt').text new File('output.txt').write(content)</lang>
Using Ant <lang groovy>new AntBuilder().copy(file:'input.txt', toFile:'output.txt', overwrite:true)</lang>
Buffered <lang groovy>new File('output.txt').withWriter( w ->
new File('input.txt').withReader( r -> w << r }
}</lang>
GUISS
<lang guiss>Start,My Documents,Rightclick:input.txt,Copy,Menu,Edit,Paste, Rightclick:Copy of input.txt,Rename,Type:output.txt[enter]</lang>
Haskell
Note: this doesn't keep the file in memory. Buffering is provided by lazy evaluation. <lang haskell>main = readFile "input.txt" >>= writeFile "output.txt"</lang>
hexiscript
<lang hexiscript>let in openin "input.txt" let out openout "output.txt" while !(catch (let c read char in))
write c out
endwhile close in; close out</lang>
HicEst
Copy via system call: <lang hicest>CHARACTER input='input.txt ', output='output.txt ', c, buffer*4096 SYSTEM(COPY=input//output, ERror=11) ! on error branch to label 11 (not shown)</lang> Read and write line by line <lang hicest>OPEN(FIle=input, OLD, ERror=21) ! on error branch to label 21 (not shown) OPEN(FIle=output)
DO i = 1, 1E300 ! "infinite" loop, exited on end-of-file error
READ( FIle=input, ERror=22) buffer ! on error (end of file) branch to label 22
WRITE(FIle=output, ERror=23) buffer ! on error branch to label 23 (not shown)
ENDDO
22 WRITE(FIle=output, CLoSe=1)</lang> Read and write in 1 block <lang hicest>OPEN(FIle=input, SEQuential, UNFormatted, OLD, LENgth=len, ERror=31) ! on error branch to label 31 (not shown) OPEN(FIle=output, SEQuential, UNFormatted, ERror=32) ! on error branch to label 32 (not shown) ALLOCATE(c, len) READ(FIle=input, CLoSe=1) c WRITE(FIle=output, CLoSe=1) c END</lang>
i
<lang i>software { file = load("input.txt") open("output.txt").write(file) } </lang>
Icon and Unicon
Icon and Unicon I/O by default is line driven. This can be changed with options in open and by the use of reads() and writes(). <lang Icon>procedure main() in := open(f := "input.txt","r") | stop("Unable to open ",f) out := open(f := "output.txt","w") | stop("Unable to open ",f) while write(out,read(in)) end</lang>
IDL
<lang idl>; open two LUNs openw,unit1,'output.txt,/get openr,unit2,'input.txt',/get
- how many bytes to read
fs = fstat(unit2)
- make buffer
buff = bytarr(fs.size)
- transfer content
readu,unit2,buff writeu,unit1,buff
- that's all
close,/all</lang>
Io
<lang io>inf := File with("input.txt") openForReading outf := File with("output.txt") openForUpdating
while(l := inf readLine,
outf write(l, "\n")
)
inf close outf close </lang>
J
<lang j> 'output.txt' (1!:2~ 1!:1)&< 'input.txt'</lang>
Or using the system library files:
<lang j>require 'files' 'output.txt' (fwrite~ fread) 'input.txt'</lang>
Note that J will read as many characters from the file as the system reports, for the size of the file. So if the system reports that the file is empty when it is not, J will return an empty result when using this file reading mechanism. (This can happen for "files" which really represent a connection to something else. When this happens, it's usually better to dedicate a separate process to reading the file.)
Java
Simple version; Files may be closed automatically by OS, on some systems.
<lang java>import java.io.*;
public class FileIODemo {
public static void main(String[] args) {
try {
FileInputStream in = new FileInputStream("input.txt");
FileOutputStream out = new FileOutputStream("ouput.txt");
int c;
while ((c = in.read()) != -1) {
out.write(c);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e){
e.printStackTrace();
}
}
}</lang>
This version closes both files after without OS intervention.
<lang java>import java.io.*;
public class FileIODemo2 {
public static void main(String args[]) {
try {
// Probably should wrap with a BufferedInputStream
final InputStream in = new FileInputStream("input.txt");
try {
// Probably should wrap with a BufferedOutputStream
final OutputStream out = new FileOutputStream("output.txt");
try {
int c;
while ((c = in.read()) != -1) {
out.write(c);
}
}
finally {
out.close();
}
}
finally {
in.close();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e){
e.printStackTrace();
}
}
}</lang>
Package nio
<lang java>import java.io.*; import java.nio.channels.*;
public class FileIODemo3 {
public static void main(String args[]) {
try {
final FileChannel in = new FileInputStream("input.txt").getChannel();
try {
final FileChannel out = new FileOutputStream("output.txt").getChannel();
try {
out.transferFrom(in, 0, in.size());
}
finally {
out.close();
}
}
finally {
in.close();
}
}
catch (Exception e) {
System.err.println("Exception while trying to copy: "+e);
e.printStackTrace(); // stack trace of place where it happened
}
}
}</lang>
This version is more in line with the other languages' implementations: it assumes simple text files, and doesn't worry too much about errors (just throws them out to the caller, the console in this case). It's shorter and simpler and shows that simple programs can be simple to write, in Java as well.
<lang java>import java.io.*; public class Test {
public static void main (String[] args) throws IOException {
BufferedReader br = new BufferedReader(new FileReader("input.txt"));
BufferedWriter bw = new BufferedWriter(new FileWriter("output.txt"));
String line;
while ((line = br.readLine()) != null) {
bw.write(line);
bw.newLine();
}
br.close();
bw.close();
}
}</lang>
<lang java5>import java.nio.file.*; public class Copy{
public static void main(String[] args) throws Exception{
FileSystem fs = FileSystems.getDefault();
Path in = fs.getPath("input.txt");
Path out = fs.getPath("output.txt");
Files.copy(in, out, StandardCopyOption.REPLACE_EXISTING);
}
}</lang>
JavaScript
<lang javascript>var fso = new ActiveXObject("Scripting.FileSystemObject"); var ForReading = 1, ForWriting = 2; var f_in = fso.OpenTextFile('input.txt', ForReading); var f_out = fso.OpenTextFile('output.txt', ForWriting, true);
// for small files: // f_out.Write( f_in.ReadAll() );
while ( ! f_in.AtEndOfStream) {
// ReadLine() does not include the newline char f_out.WriteLine( f_in.ReadLine() );
}
f_in.Close(); f_out.Close();</lang>
<lang javascript> var fs = require('fs'); require('util').pump(fs.createReadStream('input.txt', {flags:'r'}), fs.createWriteStream('output.txt', {flags:'w+'})); </lang>
jq
If the input file consists of ordinary lines of text, then the lines can be copied verbatim, one by one, as follows: <lang jq>jq -M --raw-input --raw-output '. as $line | $line' input.txt > output.txt </lang>
If the input file consists of JSON entities, and if we wish to "pretty print" each, then the following will suffice:<lang jq> jq -M '. as $line | $line' input.txt > output.txt </lang>
Julia
Here we read the content of file1 into the variable mystring. Then we write the content of string to file2. <lang Julia>mystring = read("file1", String) open(io->write(io, mystring), "file2", "w")</lang> Note however that Julia has a `cp` function to copy the content of a file to another file. <lang julia>cp("file1","file2")</lang> We can also open and close the file handles manually. <lang Julia>infile = open("file1", "r") outfile = open("file2", "w") write(outfile, read(infile, String)) close(outfile) close(infile)</lang> Here is a one-liner that guarantees that the file handle is closed even if something goes wrong during the read/write phase. <lang Julia>open(IO ->write(IO, read("file1", String)), "file2", "w")</lang>
K
<lang K>`output.txt 0:0:`input.txt</lang>
Kotlin
<lang scala>// version 1.1.2
import java.io.File
fun main(args: Array<String>) {
val text = File("input.txt").readText()
File("output.txt").writeText(text)
}</lang>
LabVIEW
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.
Lang5
<lang lang5>: puts(*) . "\n" . ;
- set-file '> swap open ;
- >>contents slurp puts ;
- copy-file
swap set-file 'fdst set fdst fout >>contents fdst close ;
'output.txt 'input.txt copy-file</lang>
Liberty BASIC
<lang lb>nomainwin
open "input.txt" for input as #f1
qtyBytes = lof( #f1)
source$ = input$( #f1, qtyBytes)
close #f1
open "output.txt" for output as #f2
#f2 source$;
close #f2
end</lang>
Lingo
<lang lingo>---------------------------------------- -- Returns file as ByteArray -- @param {string} tFile -- @return {byteArray|false}
on getBytes (tFile)
fp = xtra("fileIO").new()
fp.openFile(tFile, 1)
if fp.status() then return false
data = fp.readByteArray(fp.getLength())
fp.closeFile()
return data
end
-- Saves ByteArray to file -- @param {string} tFile -- @param {byteArray} tString -- @return {bool} success
on putBytes (tFile, tByteArray)
fp = xtra("fileIO").new()
fp.openFile(tFile, 2)
err = fp.status()
if not (err) then fp.delete()
else if (err and not (err = -37)) then return false
fp.createFile(tFile)
if fp.status() then return false
fp.openFile(tFile, 2)
if fp.status() then return false
fp.writeByteArray(tByteArray)
fp.closeFile()
return true
end</lang>
<lang lingo>data = getBytes("input.txt") putBytes("output.txt", data)</lang>
Lisaac
<lang Lisaac>Section Header
+ name := FILE_IO;
Section Public
- main <- (
+ e : ENTRY; + f : STD_FILE; + s : STRING;
e := FILE_SYSTEM.get "input.txt";
(e != NULL).if {
f ?= e.open_read_only;
(f != NULL).if {
s := STRING.create(f.size);
f.read s size (f.size);
f.close;
};
};
(s != NULL).if {
e := FILE_SYSTEM.make_file "output.txt";
(e != NULL).if {
f ?= e.open;
(f != NULL).if {
f.write s from (s.lower) size (s.count);
f.close;
};
};
};
);</lang>
Logo
<lang logo>to copy :from :to
openread :from openwrite :to setread :from setwrite :to until [eof?] [print readrawline] closeall
end
copy "input.txt "output.txt</lang>
Lua
<lang lua> inFile = io.open("input.txt", "r") data = inFile:read("*all") -- may be abbreviated to "*a";
-- other options are "*line",
-- or the number of characters to read.
inFile:close()
outFile = io.open("output.txt", "w") outfile:write(data) outfile:close()
-- Oneliner version: io.open("output.txt", "w"):write(io.open("input.txt", "r"):read("*a")) </lang>
M2000 Interpreter
Using Document Object
We can use Open for input/ Input$()/close, Open for Output/Print/close, but using a Document object is better, because Load.Doc can find the type of line breack and the coding, if it is UTF-8, UTG-16LE/BE and Ansi (we can provide another argument with specific way to open, or a Locale id for Ansi). When we save the document, we use the same format, so we preserve the coding and the line break type.
Open statement works for ANSI and using Wide for UTF-16LE only.
Here we use Edit to make Input.txt and edit some lines of text. Pressing Esc text saved to disk. Using Load.Doc we get the Input.txt, and we can display it using Report (which render text with word wrap, in M2000 console, using proportional text rendering), also if we have many lines there is a stop in each 3/4 of scrolling lines, to wait for a space bar or mouse click. After a wait for a keypress Doc$ saved to Output.txt, and we open it in editor.
We can use Edit.Doc to edit Doc$, without save and then open for edit.
We can edit thousands of lines. Document is a double linked list.
<lang M2000 Interpreter> Module FileInputOutput {
Edit "Input.txt"
Document Doc$
Load.Doc Doc$, "Input.txt"
Report Doc$
Print "Press a key:";Key$
Save.Doc Doc$, "Output.txt"
Edit "Output.txt"
} FileInputOutput </lang>
Using Buffer Object
A buffer expose real pointer (address), so here M(0) is the address of first byte, and Len(m) is the size of buffer in bytes. This buffer is not for code, but for data (no execution allowed).
<lang M2000 Interpreter> Module Using_Buffer {
M=buffer("Input.txt")
Print Len(m)
Open "Output1.txt" For Wide Output as #F
Print #F, Eval$(M);
Close #F
Edit "Output1.txt"
z=Filelen("Output1.txt")
Print z
Open "OutputAscii.txt" For Output as #F
Print #F, Eval$(M);
Close #F
Print Filelen("OutputAscii.txt")=z/2
Edit "OutputAscii.txt"
} Using_Buffer </lang>
Maple
<lang Maple> inout:=proc(filename) local f; f:=FileTools[Text][ReadFile](filename); FileTools[Text][WriteFile]("output.txt",f); end proc; </lang>
Mathematica
<lang Mathematica>SetDirectory@NotebookDirectory[]; If[FileExistsQ["output.txt"], DeleteFile["output.txt"], Print["No output yet"] ]; CopyFile["input.txt", "output.txt"]</lang>
MAXScript
<lang maxscript>inFile = openFile "input.txt" outFile = createFile "output.txt" while not EOF inFile do (
format "%" (readLine inFile) to:outFile
) close inFile close outFile</lang>
Mercury
<lang mercury>:- module file_io.
- - interface.
- - import_module io.
- - pred main(io::di, io::uo) is det.
- - implementation.
main(!IO) :-
io.open_input("input.txt", InputRes, !IO),
(
InputRes = ok(Input),
io.read_file_as_string(Input, ReadRes, !IO),
(
ReadRes = ok(Contents),
io.close_input(Input, !IO),
io.open_output("output.txt", OutputRes, !IO),
(
OutputRes = ok(Output),
io.write_string(Output, Contents, !IO),
io.close_output(Output, !IO)
;
OutputRes = error(OutputError),
print_io_error(OutputError, !IO)
)
;
ReadRes = error(_, ReadError),
print_io_error(ReadError, !IO)
)
;
InputRes = error(InputError),
print_io_error(InputError, !IO)
).
- - pred print_io_error(io.error::in, io::di, io::uo) is det.
print_io_error(Error, !IO) :-
io.stderr_stream(Stderr, !IO), io.write_string(Stderr, io.error_message(Error), !IO), io.set_exit_status(1, !IO).</lang>
mIRC Scripting Language
<lang mirc>alias Write2FileAndReadIt { .write myfilename.txt Goodbye Mike! .echo -a Myfilename.txt contains: $read(myfilename.txt,1) }</lang>
Modula-3
<lang modula3>MODULE FileIO EXPORTS Main;
IMPORT IO, Rd, Wr;
<*FATAL ANY*>
VAR
infile: Rd.T; outfile: Wr.T; txt: TEXT;
BEGIN
infile := IO.OpenRead("input.txt");
outfile := IO.OpenWrite("output.txt");
txt := Rd.GetText(infile, LAST(CARDINAL));
Wr.PutText(outfile, txt);
Rd.Close(infile);
Wr.Close(outfile);
END FileIO.</lang>
The code <*FATAL ANY*> is a pragma that tells the program to die if any exceptions (such as read/write errors) occur.
Nanoquery
<lang nanoquery>import Nanoquery.IO
input = new(File, "input.txt") output = new(File)
output.create("output.txt") output.open("output.txt")
contents = input.readAll() output.write(contents)</lang>
NetRexx
Takes advantage of some of the new path and file handling features of Java's java.nio library. <lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols nobinary
import java.nio.
parse arg infileName outfileName .
if infileName = | infileName.length = 0 then infileName = 'data/input.txt' if outfileName = | outfileName.length = 0 then outfileName = 'data/output.txt'
binaryCopy(infileName, outfileName)
return
method binaryCopy(infileName, outfileName) public static
do
infile = Paths.get('.', [String infileName])
outfile = Paths.get('.', [String outfileName])
fileOctets = Files.readAllBytes(infile)
Files.write(outfile, fileOctets, [StandardOpenOption.WRITE, StandardOpenOption.CREATE])
catch ioex = IOException ioex.printStackTrace() end
return
</lang>
Nim
Copying the file directly (without buffer): <lang nim>import os copyfile("input.txt", "output.txt")</lang>
Buffer for the entire file: <lang nim>let x = readFile("input.txt") writeFile("output.txt", x)</lang>
Line by line: <lang nim>var
i = open("input.txt")
o = open("output.txt", fmWrite)
for line in i.lines:
o.writeln(line)
i.close() o.close()</lang>
With a fixed sized buffer: <lang nim>const size = 4096
var
i = open("input.txt")
o = open("output.txt", fmWrite)
buf: array[size, char]
while i.readBuffer(buf.addr, size) > 0:
discard o.writeBuffer(buf.addr, size)
i.close() o.close()</lang>
Using memory mapping: <lang nim>import memfiles
var
i = memfiles.open("input.txt")
o = system.open("output.txt", fmWrite)
var written = o.writeBuffer(i.mem, i.size) assert(written == i.size)
i.close() o.close()</lang>
Objeck
<lang objeck>use IO;
bundle Default {
class Test {
function : Main(args : String[]) ~ Nil {
len := File->Size("input.txt");
buffer := Byte->New[len];
in := FileReader->New("input.txt");
if(in->IsOpen() <> Nil) {
in->ReadBuffer(0, len, buffer);
out := FileWriter->New("output.txt");
if(out->IsOpen() <> Nil) {
out->WriteBuffer(0, len, buffer);
out->Close();
};
in->Close();
};
}
}
}</lang>
Object Pascal
For procedural code see the Delphi code, which is perfectly fine in ObjectPascal.
For a more object oriented style one can use a TFilestream:
<lang pascal>uses
classes;
begin
with TFileStream.Create('input.txt', fmOpenRead) do
try
SaveToFile('output.txt');
finally
Free;
end;
end;</lang>
Objective-C
For copying files, using NSFileManager is preferred:
<lang objc>[[NSFileManager defaultManager] copyItemAtPath:@"input.txt" toPath:@"output.txt" error:NULL];</lang>
If you want to do it manually:
<lang objc>NSData *data = [NSData dataWithContentsOfFile:@"input.txt"];
[data writeToFile:@"output.txt" atomically:YES];</lang>
Displayed without error checking to make it more clear. In real code you will need to add lot of error checking code, and maybe use dataWithContentsOfFile:error: if you want to get error information on failure. However, this code will mostly work correctly even if input does not exist or is not accessible. dataWithContentsOfFile: will return nil, and sending nil the message writeTofile:atomically: does nothing :-)
The second argument (atomically:YES) write the content to a temporary file, and rename the temporary file to the destination file, replacing existing file.
OCaml
By line: <lang ocaml>let () =
let ic = open_in "input.txt" in
let oc = open_out "output.txt" in
try
while true do
let s = input_line ic in
output_string oc s;
output_char oc '\n';
done
with End_of_file ->
close_in ic;
close_out oc;
- </lang>
By character: <lang ocaml>let () =
let ic = open_in "input.txt" in
let oc = open_out "output.txt" in
try
while true do
let c = input_char ic in
output_char oc c
done
with End_of_file ->
close_in ic;
close_out oc;
- </lang>
(Notice that ic and oc, of type in_channel and out_channel, are buffered)
Octave
<lang octave> in = fopen("input.txt", "r", "native"); out = fopen("output.txt", "w","native"); if (in == -1)
disp("Error opening input.txt for reading.");
else if (out == -1)
disp("Error opening output.txt for writing.");
else while (1)
[val,count]=fread(in,1,"uchar",0,"native");
if (count > 0)
count=fwrite(out,val,"uchar",0,"native");
if (count == 0)
disp("Error writing to output.txt.");
end
else
break;
end
endwhile end end if (in != -1)
fclose(in);
end if (out != -1)
fclose(out);
end </lang>
Oforth
<lang Oforth>: fcopy(in, out) | f g |
File newMode(in, File.BINARY) dup open(File.READ) ->f File newMode(out, File.BINARY) dup open(File.WRITE) ->g while(f >> dup notNull) [ g addChar ] drop f close g close ;</lang>
Usage : <lang Oforth>fcopy("input.txt", "output.txt")</lang>
OpenEdge/Progress
<lang Progress (OpenEdge ABL)>COPY-LOB FROM FILE "input.txt" TO FILE "output.txt".</lang>
Oz
<lang oz>declare
class TextFile from Open.file Open.text end
In = {New TextFile init(name:"input.txt")}
Out = {New TextFile init(name:"output.txt" flags:[write text create truncate])}
proc {CopyAll In Out}
case {In getS($)} of false then skip
[] Line then
{Out putS(Line)}
{CopyAll In Out}
end
end
in
{CopyAll In Out}
{Out close}
{In close}</lang>
PARI/GP
<lang parigp>f=read("filename.in"); write("filename.out", f);</lang>
Pascal
The | FreePascal wiki gives a detailed description. For procedureal code see the Delphi examples. The ObjectPascal example is more OO coding style.
Perl
<lang perl>#!/usr/bin/perl
open my $fh_in, '<', 'input.txt' or die "could not open <input.txt> for reading: $!"; open my $fh_out, '>', 'output.txt' or die "could not open <output.txt> for writing: $!";
- '>' overwrites file, '>>' appends to file, just like in the shell
binmode $fh_out; # marks filehandle for binary content on systems where that matters
print $fh_out $_ while <$fh_in>;
- prints current line to file associated with $fh_out filehandle
- the same, less concise
- while (<$fh_in>) {
- print $fh_out $_;
- };
close $fh_in; close $fh_out;</lang>
Perl has also a powerful mechanism in conjunction with opening files called IO disciplines. It allows you to automatically apply chainable transformations on the input and output. Mangling newlines, gzip (de)compression and character encoding are the most used examples.
Phix
whole file as a single string (safe on small binary files) <lang Phix>integer fn = open("input.txt","rb") string txt = get_text(fn)
close(fn)
fn = open("output.txt","wb")
puts(fn,txt)
close(fn)</lang>
line-by-line (text files only) <lang Phix>integer infn = open("input.txt","r"),
outfn = open("output.txt","w")
object line
while 1 do
line = gets(infn)
if atom(line) then exit end if
puts(outfn,line)
end while
close(infn)
close(outfn)</lang>
byte-by-byte (safe on binary files) <lang Phix>integer byte,
infd = open("input.txt","rb"),
outfd = open("output.txt","wb")
while 1 do
byte = getc(infd)
if byte=-1 then exit end if
puts(outfd,byte)
end while
close(infd)
close(outfd)</lang>
PHP
<lang php><?php
if (!$in = fopen('input.txt', 'r')) {
die('Could not open input file.');
}
if (!$out = fopen('output.txt', 'w')) {
die('Could not open output file.');
}
while (!feof($in)) {
$data = fread($in, 512); fwrite($out, $data);
}
fclose($out); fclose($in); ?></lang>
<lang php><?php if ($contents = file_get_contents('input.txt')) {
if (!file_put_contents('output.txt', $contents)) {
echo('Could not write output file.');
}
} else {
echo('Could not open input file.');
} ?></lang>
PicoLisp
Using a variable
<lang PicoLisp>(let V (in "input.txt" (till))
(out "output.txt" (prin V)) )</lang>
Skipping intermediate variable
<lang PicoLisp>(in "input.txt"
(out "output.txt"
(echo) ) )</lang>
Pike
Line by line
<lang Pike> object lines = Stdio.File("input.txt")->line_iterator(); object out = Stdio.File("output.txt", "cw"); foreach(lines; int line_number; string line)
out->write(line + "\n");
</lang> Note that "\r" will be passed on like any other character. If line_iterator is called with the argument 1 it will however run in trim mode, and all "\r"s will be discarded.
PL/I
<lang pli> declare in file, out file;
open file (in) title ('/INPUT.TXT,type(text),recsize(100)') input; open file (out) title ('/OUTPUT.TXT,type(text),recsize(100') output; do forever;
get file (in) edit (line) (L); put file (out) edit (line) (A);
end; </lang>
Pop11
Char by char copy:
<lang pop11>lvars i_stream = discin('input.txt'); lvars o_stream = discout('output.txt'); lvars c; while (i_stream() ->> c) /= termin do
o_stream(c);
endwhile;</lang>
Low level block copy:
<lang pop11>lvars i_file = sysopen('input.txt', 0, true); lvars o_file = syscreate('output.txt', 1, true); lvars buff = inits(4096); lvars i; while (sysread(i_file, buff, length(buff)) ->> i) > 0 do
syswrite(o_file, buff, i);
endwhile;</lang>
PowerShell
Read the input file then pipe it's contents to output file. Assumes that the files are in the same folder that the script is executing in. <lang PowerShell>Get-Content $PWD\input.txt | Out-File $PWD\output.txt</lang>
Using an alternate cmdlet to write the file <lang PowerShell>Get-Content $PWD\input.txt | Set-Content $PWD\output.txt</lang>
PureBasic
Basic file copy <lang PureBasic>CopyFile("input.txt","output.txt")</lang>
Line by line
<lang PureBasic>in = ReadFile(#PB_Any,"input.txt")
If in
out = CreateFile(#PB_Any,"output.txt")
If out
Define MyLine$
While Not Eof(in)
MyLine$ = ReadString(in)
WriteString(out,MyLine$)
Wend
CloseFile(out)
EndIf
CloseFile(in)
EndIf</lang>
Reading & writing the complete file in one pass
<lang PureBasic>If ReadFile(0,"input.txt")
Define MyLine$, *Buffer, length
length=FileSize("input.txt")
*Buffer = AllocateMemory(length)
If *Buffer
If OpenFile(1,"output.txt")
ReadData(0, *Buffer, length)
WriteData(1, *Buffer, length)
CloseFile(1)
EndIf
FreeMemory(*Buffer)
EndIf
CloseFile(0)
EndIf</lang>
Python
The following use of the standard libraries shutil.copyfile is to be preferred. (Current source code ensures that failure to open files raises appropriate exceptions, a restricted buffer is used to copy the files using binary mode, and any used file descriptors are always closed).
<lang python>import shutil shutil.copyfile('input.txt', 'output.txt')</lang>
However the following example shows how one would do file I/O of other sorts:
<lang python>infile = open('input.txt', 'r') outfile = open('output.txt', 'w') for line in infile:
outfile.write(line)
outfile.close() infile.close()</lang>
This does no error checking. A more robust program would wrap each open with exception handling blocks:
<lang python>import sys try:
infile = open('input.txt', 'r')
except IOError:
print >> sys.stderr, "Unable to open input.txt for input" sys.exit(1)
try:
outfile = open('output.txt', 'w')
except IOError:
print >> sys.stderr, "Unable to open output.txt for output" sys.exit(1)
try: # for finally
try: # for I/O
for line in infile:
outfile.write(line)
except IOError, e:
print >> sys.stderr, "Some I/O Error occurred (reading from input.txt or writing to output.txt)"
finally:
infile.close() outfile.close()</lang>
In Python 2.6 (or 2.5 if we use from __future__ import with_statement) we can more simply write:
<lang python>import sys try:
with open('input.txt') as infile:
with open('output.txt', 'w') as outfile:
for line in infile:
outfile.write(line)
except IOError:
print >> sys.stderr, "Some I/O Error occurred" sys.exit(1)</lang>
The files will automatically be closed on exit of their with: blocks. (Thus even if an I/O error occurred while reading the middle of the input file we are assured that the .close() method will have been called on each of the two files.
R
If files are textual we can use readLines ("-1" means "read until the end")
<lang rsplus>src <- file("input.txt", "r") dest <- file("output.txt", "w")
fc <- readLines(src, -1) writeLines(fc, dest) close(src); close(dest)</lang>
If the files are not textual but "generic":
<lang rsplus>src <- file("input.txt", "rb") dest <- file("output.txt", "wb")
while( length(v <- readBin(src, "raw")) > 0 ) {
writeBin(v, dest)
} close(src); close(dest)</lang>
Another simpler way is to use file.copy
<lang rsplus>file.copy("input.txt", "output.txt", overwrite = FALSE)</lang>
Racket
<lang Racket>#lang racket (define file-content
(with-input-from-file "input.txt"
(lambda ()
(let loop ((lst null))
(define new (read-char))
(if (eof-object? new)
(apply string lst)
(loop (append lst (list new))))))))
(with-output-to-file "output.txt"
(lambda () (write file-content)))</lang>
Raku
(formerly Perl 6)
If it is okay to have a temporary copy of the entire file in memory:
<lang perl6>spurt "output.txt", slurp "input.txt";</lang>
Otherwise, copying line-by line:
<lang perl6>my $in = open "input.txt"; my $out = open "output.txt", :w; for $in.lines -> $line {
$out.say: $line;
} $in.close; $out.close;</lang>
RapidQ
File I/O is one of the things where RapidQ differs from standard Basic. RapidQ uses file streams.
The first version copies text line by line, as in the BASIC example.
<lang rapidq>$INCLUDE "rapidq.inc"
DIM File1 AS QFileStream DIM File2 AS QFileStream
File1.Open("input.txt", fmOpenRead) File2.Open("output.txt", fmCreate)
WHILE NOT File1.EOF
data$ = File1.ReadLine File2.WriteLine(data$)
WEND
File1.Close File2.Close</lang>
When just copying data, the code can be simplified by using the CopyFrom method.
(The second parameter for CopyFrom is number of bytes to copy, 0 = copy the whole file.)
<lang rapidq>$INCLUDE "rapidq.inc"
DIM File1 AS QFileStream DIM File2 AS QFileStream
File1.Open("input.txt", fmOpenRead) File2.Open("output.txt", fmCreate)
File2.CopyFrom(File1, 0)
File1.Close File2.Close</lang>
Raven
<lang raven>'input.txt' read 'output.txt' write</lang>
REALbasic
<lang vb> Sub WriteToFile(input As FolderItem, output As FolderItem)
Dim tis As TextInputStream Dim tos As TextOutputStream tis = tis.Open(input) tos = tos.Create(output) While Not tis.EOF tos.WriteLine(tis.ReadLine) Wend tis.Close tos.Close
End Sub </lang>
REBOL
<lang REBOL>write %output.txt read %input.txt
- No line translations
write/binary %output.txt read/binary %input.txt
- Save a web page
write/binary %output.html read http://rosettacode.org </lang>
Red
<lang Red> file: read %input.txt write %output.txt file</lang>
Retro
<lang Retro>with files' here dup "input.txt" slurp "output.txt" spew</lang>
REXX
In REXX, filename association is used rather than numeric stream numbers and explicit file opening is not required.
version 1
The two optional REXX statements are only needed if there is another REXX program in the invocation chain
(which may have invoked this program) that already has one of the input and/or output files open.
The two best programming practice REXX statements are only needed if there is another calling program in the invocation chain
(which may want to (re-)use the two files just used.
<lang rexx>/*REXX program reads a file and copies the contents into an output file (on a line by line basis).*/
iFID = 'input.txt' /*the name of the input file. */
oFID = 'output.txt' /* " " " " output " */
call lineout iFID,,1 /*insure the input starts at line one.*/ /* ◄■■■■■■ optional.*/
call lineout oFID,,1 /* " " output " " " " */ /* ◄■■■■■■ optional.*/
do while lines(iFID)\==0; $=linein(iFID) /*read records from input 'til finished*/
call lineout oFID, $ /*write the record just read ──► output*/
end /*while*/ /*stick a fork in it, we're all done. */
call lineout iFID /*close input file, just to be safe.*/ /* ◄■■■■■■ best programming practice.*/ call lineout oFID /* " output " " " " " */ /* ◄■■■■■■ best programming practice.*/</lang>
version 2
Note that this version is limited to files less than one million bytes (and/or possibly virtual memory). <lang rexx>/*REXX program to read a file and write contents to an output file*****
- 03.09.2012 Walter Pachl (without erase string would be appended)
- /
ifid='input.txt' /*name of the input file. */ ofid='output.txt' /*name of the output file. */ 'erase' ofid /* avoid appending */ s=charin(ifid,,1000000) /* read the input file */ Call charout ofid,s /* write to output file */</lang>
Ring
<lang ring> fn1 = "ReadMe.txt" fn2 = "ReadMe2.txt"
fp = fopen(fn1,"r") str = fread(fp, getFileSize(fp)) fclose(fp)
fp = fopen(fn2,"w") fwrite(fp, str) fclose(fp) see "OK" + nl
func getFileSize fp
c_filestart = 0
c_fileend = 2
fseek(fp,0,c_fileend)
nfilesize = ftell(fp)
fseek(fp,0,c_filestart)
return nfilesize
</lang>
Ruby
In general, open both files in binary mode.
<lang ruby>str = File.open('input.txt', 'rb') {|f| f.read} File.open('output.txt', 'wb') {|f| f.write str}</lang>
If 'input.txt' is a text file, we may forget binary mode. If no pathname begins with a pipe '|', then we may use IO::read and Kernel#open. (The pipe is a problem, because IO.read('| uname') or open('| sh', 'w') would open a subprocess and not a file.)
<lang ruby># Only if 'input.txt' is a text file!
- Only if pipe '|' is not first character of path!
str = IO.read('input.txt') open('output.txt', 'w') {|f| f.write str}</lang>
To copy a file block by block, use FileUtils from the standard library.
<lang ruby>require 'fileutils' FileUtils.copy_file 'input.txt', 'output.txt'</lang>
Run BASIC
<lang runbasic>open "input.txt" for input as #in fileLen = LOF(#in) 'Length Of File fileData$ = input$(#in, fileLen) 'read entire file close #in
open "output.txt" for output as #out print #out, fileData$ 'write entire fie close #out end
' or directly with no intermediate fileData$
open "input.txt" for input as #in open "output.txt" for output as #out fileLen = LOF(#in) 'Length Of File print #out, input$(#in, fileLen) 'entire file close #in close #out </lang>
Rust
<lang rust>use std::fs::File; use std::io::{Read, Write};
fn main() {
let mut file = File::open("input.txt").unwrap();
let mut data = Vec::new();
file.read_to_end(&mut data).unwrap();
let mut file = File::create("output.txt").unwrap();
file.write_all(&data).unwrap();
} </lang> The above program will panic with any sort of error. The following shows proper error handling: <lang rust>use std::fs::File; use std::io::{self, Read, Write}; use std::path::Path; use std::{env, fmt, process};
fn main() {
let files: Vec<_> = env::args_os().skip(1).take(2).collect();
if files.len() != 2 {
exit_err("Both an input file and output file are required", 1);
}
copy(&files[0], &files[1]).unwrap_or_else(|e| exit_err(&e, e.raw_os_error().unwrap_or(-1)));
}
fn copy<P: AsRef<Path>>(infile: P, outfile: P) -> io::Result<()> {
let mut vec = Vec::new();
Ok(try!(File::open(infile)
.and_then(|mut i| i.read_to_end(&mut vec))
.and_then(|_| File::create(outfile))
.and_then(|mut o| o.write_all(&vec))))
}
fn exit_err<T: fmt::Display>(msg: T, code: i32) -> ! {
writeln!(&mut io::stderr(), "ERROR: {}", msg).expect("Could not write to stdout");
process::exit(code);
}</lang>
Scala
<lang scala>import java.io.{ FileNotFoundException, PrintWriter }
object FileIO extends App {
try {
val MyFileTxtTarget = new PrintWriter("output.txt")
scala.io.Source.fromFile("input.txt").getLines().foreach(MyFileTxtTarget.println)
MyFileTxtTarget.close()
} catch {
case e: FileNotFoundException => println(e.getLocalizedMessage())
case e: Throwable => {
println("Some other exception type:")
e.printStackTrace()
}
}
}</lang>
Scheme
Character by character copy<lang scheme>; Open ports for the input and output files (define in-file (open-input-file "input.txt")) (define out-file (open-output-file "output.txt"))
- Read and write characters from the input file
- to the output file one by one until end of file
(do ((c (read-char in-file) (read-char in-file)))
((eof-object? c))
(write-char c out-file))
- Close the ports
(close-input-port in-file) (close-output-port out-file) </lang>
Seed7
The library osfiles.s7i contains the function copyFile which can be used to copy a source file to a destination.
<lang seed7>$ include "seed7_05.s7i";
include "osfiles.s7i";
const proc: main is func
begin
copyFile("input.txt", "output.txt");
end func;</lang>
SenseTalk
Reading the file all at once: <lang sensetalk>put file "input.txt" into fileContents put fileContents into file "output.txt"</lang> Reading the file line by line: <lang sensetalk>put "input.txt" into inputFile put "output.txt" into outputFile
open file inputFile open file outputFile for writing
repeat forever read from file inputFile until return if it is empty then exit repeat write it to file outputFile end repeat
close file inputFile close file outputFile</lang>
Sidef
<lang ruby>var in = %f'input.txt'.open_r; var out = %f'output.txt'.open_w;
in.each { |line|
out.print(line);
};</lang>
Slate
<lang slate>(File newNamed: 'input.txt' &mode: File Read) sessionDo: [| :in |
(File newNamed: 'output.txt' &mode: File CreateWrite) sessionDo: [| :out | in >> out]]</lang>
Smalltalk
<lang smalltalk>| in out | in := FileStream open: 'input.txt' mode: FileStream read. out := FileStream open: 'output.txt' mode: FileStream write. [ in atEnd ]
whileFalse: [
out nextPut: (in next)
]</lang>
Snabel
Reads the entire file into into a list of buffers before writing and returns number of bytes written. <lang snabel> let: q Bin list; 'input.txt' rfile read {{@q $1 push} when} for @q 'output.txt' rwfile write 0 $1 &+ for </lang>
Alternative solution for large files with comparable performance to shell cp; also returns number of bytes written. <lang snabel> let: q Bin list; let: wq @q fifo; let: w 'output.txt' rwfile @wq $1 write;
'input.txt' rfile read 0 $1 {{
$ @q $1 push len + @w &break _for
} when} for
@q +? {@w &_ for} when </lang>
SNOBOL4
<lang snobol4>
input(.input,5,,'input.txt')
output(.output,6,,'output.txt')
while output = input :s(while) end</lang>
Standard ML
<lang sml>fun copyFile (from, to) = let
val instream = TextIO.openIn from val outstream = TextIO.openOut to val () = TextIO.output (outstream, TextIO.inputAll instream) val () = TextIO.closeIn instream val () = TextIO.closeOut outstream
in
true
end handle _ => false;</lang>
Stata
Stata has a copy command. Here is a way to implement this by reading and writing line by line. <lang stata>program copyfile file open fin using `1', read text file open fout using `2', write text replace
file read fin line while !r(eof) { file write fout `"`line'"' _newline file read fin line } file close fin file close fout end
copyfile input.txt output.txt</lang>
Tcl
<lang tcl>set in [open "input.txt" r] set out [open "output.txt" w]
- Obviously, arbitrary transformations could be added to the data at this point
puts -nonewline $out [read $in] close $in close $out</lang> For larger files, it is better to use the fcopy command, though in general this restricts what operations can be performed rather more (only encoding and end-of-line translations are possible — or more general byte-level transformations with the generic filter mechanism provided in Tcl 8.6 — none of which are shown here): <lang tcl>set in [open "input.txt" r] set out [open "output.txt" w] fcopy $in $out close $in close $out</lang> Or the minimal version if we don't need any processing of the data at all: <lang tcl>file copy input.txt output.txt</lang>
Other key file I/O operations
- Writing a line to a file:
<lang tcl>#open file for writing set myfile [open "README.TXT" w]
- write something to the file
puts $myfile "This is line 1, so hello world...."
- close the file
close $myfile</lang>
- Reading a line from a file:
<lang tcl>#open file for reading set myfile [open "README.TXT" r]
- read something from the file
gets $myfile mydata
- show what was read from the file
- should print "This is line1, so hello world...."
puts $mydata
- close the file
close $myfile</lang>
Toka
This is one method, which works with any type of file:
<lang toka>( source dest -- ) {
value| source dest size buffer |
{
{
[ "W" file.open to dest ] is open-dest
[ "R" file.open to source ] is open-source
[ open-dest open-source ]
} is open-files
{
[ source file.size to size ] is obtain-size
[ size malloc to buffer ] is allocate-buffer
[ obtain-size allocate-buffer ]
} is create-buffer
[ source dest and 0 <> ] is check
[ open-files create-buffer check ]
} is prepare
[ source buffer size file.read drop ] is read-source
[ dest buffer size file.write drop ] is write-dest
[ source file.close dest file.close ] is close-files
[ prepare [ read-source write-dest close-files ] ifTrue ]
} is copy-file</lang>
And a much simpler way for plain text files, making use of file.slurp:
<lang toka>[ ( source dest -- )
swap file.slurp dup 0 <> [ >r "W" file.open dup r> string.getLength file.write drop file.close ] ifTrue
] is copy-file</lang>
And a test:
<lang toka>" input.txt" " output.txt" copy-file</lang>
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT ERROR/STOP CREATE ("input.txt", seq-o,-std-) ERROR/STOP CREATE ("output.txt",seq-o,-std-)
FILE/ERASE "input.txt" = "Some irrelevant content" path2input =FULLNAME(TUSTEP,"input.txt", -std-) status=READ (path2input,contentinput)
path2output=FULLNAME(TUSTEP,"output.txt",-std-) status=WRITE(path2output,contentinput) </lang>
TXR
As a character string:
<lang txrlisp>(let ((var (file-get-string "input.txt")))
(file-put-string "output.txt" var))</lang>
As a list of lines:
<lang txrlisp>(let ((var (file-get-lines "input.txt")))
(file-put-lines "output.txt" var))</lang>
UNIX Shell
Using the 'read' built-in
- Hint: mksh(1) manual says, "If read is run in a loop such as while read foo; do ...; done then leading whitespace will be removed (IFS) and backslashes processed. You might want to use while IFS= read -r foo; do ...; done for pristine I/O."
- Caveat: output.txt will end with a newline, whether or not input.txt ended with one.
<lang bash>#!/bin/sh while IFS= read -r a; do
printf '%s\n' "$a"
done <input.txt >output.txt</lang>
Another way, using the 'cat' program
<lang bash>#!/bin/sh cat input.txt >output.txt</lang>
Yet another way, using the 'cp' utility <lang bash>#!/bin/sh cp input.txt output.txt</lang>
Ursa
<lang ursa>decl file input output decl string contents input.open "input.txt" output.create "output.txt" output.open "output.txt" set contents (input.readall) out contents output</lang>
Ursala
I/O in Ursala is meant to be handled transparently by the run time system. The application is passed the input files as an argument and expected to return the output files as a result.
Returning a copy of the input file with a new name causes it to be written as a new file. <lang Ursala>#import std
- executable ('parameterized',)
fileio = ~command.files; &h.path.&h:= 'output.txt'!</lang>
VBA
<lang vb>Option Explicit
Sub Main() Dim s As String, FF As Integer
'read a file line by line FF = FreeFile Open "C:\Users\" & Environ("username") & "\Desktop\input.txt" For Input As #FF While Not EOF(FF)
Line Input #FF, s Debug.Print s
Wend Close #FF
'read a file FF = FreeFile Open "C:\Users\" & Environ("username") & "\Desktop\input.txt" For Input As #FF
s = Input(LOF(1), #FF)
Close #FF Debug.Print s
'write a file FF = FreeFile Open "C:\Users\" & Environ("username") & "\Desktop\output.txt" For Output As #FF
Print #FF, s
Close #FF End Sub</lang>
VBScript
one liner (-2 for system default encoding) <lang vb>CreateObject("Scripting.FileSystemObject").OpenTextFile("output.txt",2,-2).Write CreateObject("Scripting.FileSystemObject").OpenTextFile("input.txt", 1, -2).ReadAll</lang>
Vedit macro language
An edit buffer is normally used as "string variable" in Vedit. To read a file into edit buffer, simply open the file. The file contents can then be modified if required before saving into a new file. <lang vedit>File_Open("input.txt") File_Save_As("output.txt", NOMSG) Buf_Close(NOMSG) </lang>
Visual Basic .NET
<lang vbnet>'byte copy My.Computer.FileSystem.WriteAllBytes("output.txt", _
My.Computer.FileSystem.ReadAllBytes("input.txt"), False)
'text copy Using input = IO.File.OpenText("input.txt"), _
output As New IO.StreamWriter(IO.File.OpenWrite("output.txt"))
output.Write(input.ReadToEnd)
End Using
'Line by line text copy Using input = IO.File.OpenText("input.txt"), _
output As New IO.StreamWriter(IO.File.OpenWrite("output.txt"))
Do Until input.EndOfStream
output.WriteLine(input.ReadLine)
Loop
End Using</lang>
Wart
<lang wart>with infile "input.txt"
with outfile "output.txt"
whilet line (read_line)
prn line</lang>
Wren
<lang ecmascript>import "io" for File
var contents = File.read("input.txt") File.create("output.txt") {|file|
file.writeBytes(contents)
}</lang>
XPL0
Usage: fileio <input.txt >output.txt
<lang XPL0>include c:\cxpl\codes; int I, C; char IntermediateVariable; [IntermediateVariable:= GetHp; I:= 0; repeat C:= ChIn(1);
IntermediateVariable(I):= C;
I:= I+1;
until C = $1A; \EOF I:= 0; repeat C:= IntermediateVariable(I);
I:= I+1;
ChOut(0, C);
until C = $1A; \EOF ]</lang>
zkl
<lang zkl>var d=File("input.txt").read(); (f:=File("output.txt","w")).write(d); f.close(); // one read, one write copy File("output.txt").pump(Console); // verify by printing</lang> It might be considered "good form" to immediately close files (rather than wait for the garbage collector to do it) as these are system resources. <lang zkl>var in=File("input.txt"), out=File("output.txt","w"); foreach line in (in) { out.write(line) } // copy line by line out.close(); // or out=Void and let GC close the file</lang> <lang zkl>fin,fout:=File("input.txt","rb"), File("output.txt","wb"); // copy in chunks, implicit buffer fin.pump(Data(0d524_287),fout); fin.close(); fout.close();</lang> <lang zkl>// copy in chunks, let GC close file handles File("input.txt","rb").pump(Data(0d524_287),File("output.txt","wb"));</lang> In these last two, the implicit buffer (whose size if given by the numbers) is visible inside the pump. Consider this example, which converts input to upper case text on its way to output (the Data() is optional; using it chunks, without, lines): <lang zkl>File("input.txt").pump(Data(),File("output.txt","w"),"text","toUpper");</lang>
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