File input/output: Difference between revisions
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Close (Output); |
Close (Output); |
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end File_IO; |
end File_IO; |
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==[[BASIC]]== |
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'''Compiler:''' [[QuickBasic]] 4.5 |
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OPEN "INPUT.TXT" FOR INPUT AS #1 |
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OPEN "OUTPUT.TXT" FOR OUTPUT AS #2 |
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DO UNTIL EOF(1) |
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LINE INPUT #1, Data$ |
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PRINT #2, Data$ |
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LOOP |
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CLOSE #1 |
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CLOSE #2 |
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SYSTEM |
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==[[C]]== |
==[[C]]== |
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Revision as of 06:31, 23 January 2007
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
Compiler: GCC 4.1.2
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;
BASIC
Compiler: QuickBasic 4.5
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
C
Compiler: GCC 4.1.2
#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;
}
C#
Platform: .NET Language Version: 1.0+
using System;
using System.IO;
namespace FileIO
{
class Program
{
static void Main(string[] args)
{
if (File.Exists("input.txt"))
{
TextReader tr = File.OpenText("input.txt");
TextWriter tw = new StreamWriter(File.OpenWrite("output.txt"));
while (tr.Peek() != -1)
{
string line = tr.ReadLine();
tw.WriteLine(line);
}
tw.Close();
tr.Close();
}
else
{
Console.WriteLine("Input File Missing.");
}
}
}
}
C++
Compiler: GCC 3.4.2
#include <iostream>
#include <fstream>
#include <string>
int main() {
string line;
ifstream input ( "input.txt" );
ofstream output ("output.txt");
if (output.is_open()) {
if (input.is_open()){
while (! input.eof() ) {
getline (input,line);
output << line << endl;
}
input.close();
}
else {
cout << "input.txt cannot be opened!\n";
}
output.close();
}
else {
cout << "output.txt cannot be written to!\n";
}
return 0;
}
Simpler version:
#include <iostream>
#include <istream>
#include <ostream>
#include <fstream>
#include <cstdlib>
int main()
{
std::ifstream input("input.txt");
if (!input)
{
std::cerr << "could not open input.txt for reading.\n";
return EXIT_FAILURE;
}
std::ofstream output("output.txt");
if (!output)
{
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;
}
Using istream- and ostream- iterators:
# 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));
}
Java
Compiler: GCJ 4.1.2
Simple version; files are closed by OS when the program finishes
[EDIT: Are you sure they automatically close? I read nothing in the standard API to that effect.]
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 (Exception e) {
e.printStackTrace();
}
}
}
This version closes both files after without OS intervention
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 (Exception e) {
System.err.println("Exception while trying to copy: "+e);
e.printStackTrace(); // stack trace of place where it happened
}
}
}
This version uses the newer (1.4 onwards) nio package.
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
}
}
}
Perl
Interpreter: Perl 5.8.8
#!/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 $fh_out;
Perl has also a powerful mechanism in conjunction with opening files called IO disciplines. It allows you to automatically apply chainable transformations on the input and output. Mangling newlines, gzip (de)compression and character encoding are the most used examples.
PHP
Interpreter: PHP 4
<?php
if (!$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);
?>
Interpreter: PHP 5
<?php
if( $contents = file_get_contents('input.txt') ){
if( !file_put_contents('output.txt') ) echo('could not write output file');
}else{
echo('could not open input file');
}
?>
mIRC
Compiler: mIRC
alias Write2FileAndReadIt {
.write myfilename.txt Goodbye Mike!
.echo -a Myfilename.txt contains: $read(myfilename.txt,1)
}
Python
Interpreter: Python 2.4
In short form:
open("output.txt", "w").writelines(open("input.txt"))
With proper closing and exception-handling:
inputFile = open("input.txt","r")
try:
outputFile = open("output.txt", "w")
try:
outputFile.writelines(inputFile)
finally:
outputFile.close()
finally:
inputFile.close()
Ruby
Interpreter: Ruby 1.8.4
begin
File.open("output.txt","w") {|f| f << IO.read("input.txt")}
rescue Exception => e
$stderr.puts "Exception raised: #{e}"
end
TCL
Interpreter: tclsh, eTcl, wish, tixwish
set in [open "input.txt" r] set out [open "output.txt" w] puts -nonewline $out [read $in] close $in close $out
Other File I/O:
#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
#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 $myfile
UNIX Shell
Interpreter: Bourne Shell Operating System: UNIX
#!/bin/sh
while read a; do
echo "$a"
done <input.txt >output.txt
#!/bin/sh # another way, using the 'cat' program cat input.txt >output.txt
# yet another way, using the 'cp' utility cp input.txt output.txt