File input/output

File input/output
You are encouraged to solve this task according to the task description, using any language you may know.

In this task, the job is to create a file called "output.txt", and place in it the contents of the file "input.txt".

Ada

If the file line size exceeds the size of the input string the output file will contain extra new-line characters. <lang ada> with Ada.Text_IO; use Ada.Text_IO; procedure File_IO is

  Input, Output : File_Type;
  Line : String (1 .. 10_000);
  Last : Natural;

begin

  Create (Output, Out_File, "output.txt");
  Open (Input, In_File, "input.txt");
  while not End_Of_File (Input) loop
     Get_Line (Input, Line, Last);
     Put_Line (Output, Line (1 .. Last));
  end loop;
  Close (Input);
  Close (Output);

end File_IO; </lang> Note that it is possible to use a version of Get_Line that returns the read line as one string of unspecified length: <lang ada> while not End_Of_File (Input) loop

  Put_Line (Output, Get_Line (Input));

end loop; </lang> But it is not recommended, because it would make program vulnerable to storage error problems.

The following example reads and writes each file one character at a time. There is no new-line issue. <lang ada> with Ada.Sequential_Io;

procedure File_Io is

  package Char_Io is new Ada.Sequential_Io(Character);
  use Char_Io;
  Infile, Outfile : File_Type;
  Value : Character;

begin

  Create(File => Outfile, Mode => Out_File, Name => "output.txt");
  Open(File => Infile, Mode => In_File, Name => "input.txt");
  while not End_Of_File(Infile) loop
     Read(File => Infile,  Item => Value);
     Write(File => Outfile, Item => Value);
  end loop;
  Close(Infile);
  Close(Outfile);

end File_IO; </lang> 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. Note also how End_Error exception is used to avoid End_Of_File. End_Of_File is depreciated as it requires file look-ahead, and thus is much less efficient. <lang ada> with Ada.Text_IO; use Ada.Text_IO; with Ada.Text_IO.Text_Streams; use Ada.Text_IO.Text_Streams;

procedure File_Io is

  Infile, Outfile : File_Type;

begin

  Create (File => Outfile, Mode => Out_File, Name => "output.txt");
  Open (File => Infile, Mode => In_File, Name => "input.txt");
  loop
     Character'Write (Stream (Outfile), Character'Input (Stream (Infile)));
  end loop;

exception

  when End_Error =>
     Close (Infile);
     Close (Outfile);

end File_IO; </lang>

ALGOL 68

PROC copy file = (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);

  BOOL in done := FALSE;
  PROC call back done = (REF FILE f) BOOL: ( in done := TRUE );
  on logical file end(in file, call back done);

  STRING line;
  WHILE
    get(in file,(line, new line));
    NOT in done
  DO
    put(out file,(line, new line))
  OD;
  close(in file);
  close(out file)
);

copy file("input.txt","output.txt")

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"

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 IO. <lang autohotkey>FileCopy, input.txt, output.txt</lang>

Binary IO 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>

BASIC

Works with: QuickBasic version 4.5

<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>

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.

It uses buffered IO to perform the move, which is overkill. This is not actually a weakness, but it invokes some overhead that you don't need.

The following example addresses those issues. To avoid buffered IO, it uses open(), read(), write() and close(), which are part of POSIX, but not defined of ANSI C.

Works with: POSIX

<lang c> #include <stdio.h>

 #include <unistd.h>
 #include <fcntl.h>
 
 int main(int argc, char **argv)
 { int   fi, fo;
   int   len;
   char  buf[1024];  /* a better choice is the FS block size, if you know it */
 
   if ((fi = open("input.txt", O_RDONLY)) < 0) {
     perror("Can't read input.txt");
     return 1;
   }
 
   if ((fo = open("output.txt", O_WRONLY|O_CREAT|O_TRUNC)) < 0) {
     perror("Can't write to output.txt");
     return 1;
   }
 
   while ((len = read(fi, buf, 1024)) > 0) {
     if (write(fo, buf, len) < 0) {
       perror("write failed");
       return 1;
     }
   }
 
   if (len < 0) {
     perror("read failed");
     return 1;
   }
 
   close(fi); close(fo);
   return 0;
 }</lang>

C#

<lang csharp>using System.IO;

string input = new StreamReader("input.txt").ReadToEnd(); StreamWriter output = new StreamWriter("output.txt");

output.Write(input); output.Close();</lang>

C++

Works with: g++ version 3.4.2

<lang cpp>#include <iostream>

1. include <fstream>
2. 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 (input) {
               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>

1. include <fstream>
2. 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>

1. 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.

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

Apply this function to the world to copy a file.

Start world = copyFile "input.txt" "output.txt" world

ColdFusion

<cfif fileExists(expandPath("input.txt"))>
  <cffile action="read" file="#expandPath('input.txt')#" variable="inputContents">
  <cffile action="write" file="#expandPath('output.txt')#" output="#inputContents#">
</cfif>

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

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>

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>

E

Works with: E-on-Java

<file:output.txt>.setText(<file:input.txt>.getText())

(This version holds the entire contents in memory.)

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.

\ <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

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.

Fortran

Works with: Fortran version 2003

Works with: gfortran version 4.3.2

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(len=1) :: 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>

Groovy

Using File

new File('output.txt').write(new File('input.txt').text)

Using Ant

new AntBuilder().copy(file:'input.txt', toFile:'output.txt', overwrite:true)

Buffered

new File('output.txt').withWriter( w ->
  new File('input.txt').withReader( r -> w << r }
}

Haskell

Works with: GHC

Note: this doesn't keep the file in memory. Buffering is provided by lazy evaluation. <lang haskell> copyFile from to = do

    filedata <- readFile from
    writeFile to filedata

main = copyFile "input.txt" "output.txt"</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

J

   'output.txt' (1!:2~ 1!:1)&< 'input.txt'

Java

Works with: GCJ version 4.1.2

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>

Works with: Java version 1.4

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"));
     for (String line; (line = br.readLine()) != null; ) {
       bw.write(line);
       bw.newLine();
     }
     br.close();
     bw.close();
   }
 }</lang>

Logo

Works with: UCB 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>

MAXScript

inFile = openFile "input.txt"
outFile = createFile "output.txt"
while not EOF inFile do
(
    format "%" (readLine inFile) to:outFile
)
close inFile
close outFile

mIRC Scripting Language

Works with: mIRC

 alias Write2FileAndReadIt {
 .write myfilename.txt Goodbye Mike!
 .echo -a Myfilename.txt contains: $read(myfilename.txt,1)
 }

Objective-C

Works with: Cocoa

Works with: GNUstep

Read the contents of input.txt and place it in output.txt, creating a file if needed:

<lang objc> NSData *input = [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 exists or 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)

Perl

Works with: Perl version 5.8.8

<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.

PHP

Works with: PHP version 4

<lang php> <?php

 if (!$in=fopen('input.txt','r')) {
       die('Could not open input.txt!');
 }
 
 if (!$out=fopen('output.txt','w')) {
       die('Could not open output.txt!');
 }
 
 while(!feof($in)) {
       $data = fread($in,512);
       fwrite($out,$data);
 }
 
 fclose($out);
 fclose($in);
 ?>

</lang>

Works with: PHP version 5

<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>

Pop11

Char by char copy:

lvars i_stream = discin('input.txt');
lvars o_stream = discout('output.txt');
lvars c;
while (i_stream() ->> c) /= termin do
    o_stream(c);
endwhile;

Low level block copy:

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;

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.

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.

 $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

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.)

 $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

Raven

'input.txt' read 'output.txt' write

Ruby

Works with: Ruby version 1.8.4

<lang ruby> File.open("output.txt", "w") do |file|

  file.write File.read("input.txt")
end</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>

Standard ML

Works with: SML/NJ version 110.59

 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;

Tcl

Works with: tclsh

Works with: eTcl

Works with: wish

Works with: tixwish

<lang tcl>set in [open "input.txt" r] set out [open "output.txt" w]

1. 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, though not 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 File I/O:

<lang tcl>#open file for writing set myfile [open "README.TXT" w]

1. write something to the file

puts $myfile "This is line 1, so hello world...."

1. close the file

close $myfile</lang>

<lang tcl>#open file for reading set myfile [open "README.TXT" r]

1. read something from the file

gets $myfile mydata

1. show what was read from the file
2. should print "This is line1, so hello world...."

puts $mydata

1. close the file

close $myfile</lang>

Toka

This is one method, which works with any type of file:

( 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

And a much simpler way for plain text files, making use of file.slurp:

 [ ( source dest -- ) 
   swap file.slurp dup 0 <>
   [ >r "W" file.open dup r> string.getLength file.write drop file.close ] ifTrue
 ] is copy-file

And a test:

 " input.txt" " output.txt" copy-file

UNIX Shell

Bourne Shell

<lang bash> #!/bin/sh

while read a; do
    echo "$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>

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

1. executable ('parameterized',)

fileio = ~command.files; &h.path.&h:= 'output.txt'!</lang>

Visual Basic .NET

Works with: Visual Basic .NET version 9.0+

<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>