Check that file exists: Difference between revisions

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if exist docs echo The following directory called docs exists.
if exist docs echo The following directory called docs exists.
if exist \docs\ echo The following directory called \docs\ exists.
if exist \docs\ echo The following directory called \docs\ exists.

==[[Tcl]]==
[[Category:Tcl]]

Taking the meaning of the task from the DOS example:

if { [file exists input.txt] } { puts "input.txt exists" }
if { [file exists [file nativename /input.txt]] } { puts "/input.txt exists" }

if { [file isdirectory docs] } { puts "docs exists and is a directory" }
if { [file isdirectory [file nativename /docs]] } { puts "/docs exists and is a directory" }

Revision as of 05:36, 8 April 2007

Task
Check that file exists
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 verify that a file called "input.txt" exists or not and that the directory called "docs" exists or not. Assuming current directory or fullpath. Either "/input.txt" or "\input.txt" for the former and "/docs/" or "\docs\" for the second test.


Java

import java.util.File;
public class FileExistsTest {
   public static boolean isFileExists(String filename) {
       boolean exists = new File(filename).exists();
       return exists;
   }
   public static void test(String type, String filename) {
       System.out.println("The following " + type + " called " + filename + 
           (isFileExists(filename) ? " exists." : " not exists.")
       );
   }
   public static void main(String args[]) {
        test("file", "input.txt");
        test("file", File.seperator + "input.txt");
        test("directory", "docs");
        test("directory", File.seperator + "docs" + File.seperator);
   }
}

Perl

  #!/usr/bin/perl
  sub isFileExists($) {
      my ($filename) = @_;
      return -e $filename;
  }
  sub test($$) {
      my ($type, $filename) = @_;
      print "The following " . $type . " called " . $filename . 
          (isFileExists($filename) ? " exists." : " not exists.");
  }
  my $FileSeperator = ($^O eq "MSWin32") ? "\\" : "/";
  test("file", "input.txt");
  test("file", $FileSeperator . "input.txt");
  test("directory", "docs");
  test("directory", $FileSeperator ."docs". $FileSeperator);
  exit;


  # Short version
  my $FileSeperator = ($^O eq "MSWin32") ? "\\" : "/";
  print -e 'input.txt';
  print -e $FileSeperator.'input.txt';
  print -e 'docs';
  print -e $FileSeperator.'docs'.$FileSeperator;


DOS

 if exist input.txt echo The following file called input.txt exists.
 if exist \input.txt echo The following file called \input.txt exists.
 if exist docs echo The following directory called docs exists.
 if exist \docs\ echo The following directory called \docs\ exists.

Tcl

Taking the meaning of the task from the DOS example:

if { [file exists input.txt] } { puts "input.txt exists" } 
if { [file exists [file nativename /input.txt]] } { puts "/input.txt exists" } 
if { [file isdirectory docs] } { puts "docs exists and is a directory" } 
if { [file isdirectory [file nativename /docs]] } { puts "/docs exists and is a directory" }