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Newbie question in Perl

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From:
Anand Ramakrishna
Date:
December 30, 2002 01:56
Subject:
Newbie question in Perl
Message ID:
372DD7320F873B43929D49BFF86F950BAE7556@cdc1.chennai.corp.hexaware.com
 
Hi,
    I am a beginner to perl. I have written a simple program in Perl 
# This Program will copy the contents of a file named file.txt to another file
# newfile.txt. If newfile.txt is already existing, the user is given an option
# to overwrite the file and chose a new file name to write the output.

In this program, when I initially dont have a file named newfile.txt, it goes fine. If it finds a newfile.txt, then it prompts with a Warning message whether to overwrite or use another file name text.txt. From here if I give a command to overwrite, it works fine. If I give a command NO, it still overwrites the newfile.txt. Even if I give some invalid command other than Y or N it still overwrites that file. I am unable to fix this. Kindly help me in this regard. I have pasted the entire code below.


#!/usr/local/bin/perl

# This Program will copy the contents of a file named file.txt to another file
# newfile.txt. If newfile.txt is already existing, the user is given an option
# to overwrite the file and chose a new file name to write the output.

# Open the first file file.txt

  open (FILE, "file.txt") || die ("ERROR !! file.txt does not exist\n");

# Check for newfile.txt

  if (-e "newfile.txt")
    {
      print "WARNING !! FILE newfile.txt already exists\n";
      print "Do you want to destroy all the contents and overwrite the file\n";
      print "Type Y for Yes or N or NO\n";
      $test = <STDIN>;
      $test = chomp ($test);

# Check if the command is either Yes or No. If not, be in the loop till
# Yes or No command is given.

      until (($test ne 'Y') && ($test ne 'N') &&
             ($test ne 'y') && ($test ne 'n'))
        {
          print "Type Y for Yes or N for NO\n";
          $test = <STDIN>;
          $test = chop ($test);
        }

# If command is NO, then ask if the contents will be copied in another file
# name text.txt.

      if ($test eq 'N' || $test eq 'n')
        {
          print "Do you want to write to another file named text.txt\n";
          print "Type Y for Yes or N to quit\n";
          $var = <STDIN>;
          $var = chop ($var);

# Check if the command is either Yes or No. If not, be in the loop till
# Yes or No command is given.

          until ($var ne 'Y' && $var ne 'N' && $var ne 'y' && $var ne 'n')
            {
              print "Type Y for Yes or N to quit\n";
              $var = <STDIN>;
              $var = chomp ($var);
            }

# If command is YES, copy the contents to a new file called text.txt.
# If command is NO quit program without copying.

          if ($var eq "Y" || $var eq "y")
            {
              open (FILE1, ">text.txt");
              $line1 = <FILE>;

              while ($line1 ne "")
                {
                  print FILE1 $line1;
                  $line1 = <FILE>;
                }
             }
           else
             {
               die "Program terminated without copying the file\n";
             }
        }

# Destroy the contents of newfile.txt and copy the contents in this file.

      else
        {
           open (FILE1, ">newfile.txt");
           $line1 = <FILE>;

           while ($line1 ne "")
             {
                print FILE1 $line1;
                $line1 = <FILE>;
             }
        }
    }

# If newfile.txt does not exist, create a file in that name and copy the
# contents to this file.

  else
    {
      open (FILE1, ">newfile.txt");
      $line1 = <FILE>;

      while ($line1 ne "")
        {
           print FILE1 $line1;
           $line1 = <FILE>;
        }
    }


Anbudan, 
Anand~ 
  
----------------------------------------------------------------------------------- 
If you can't beat your computer at Chess, try kickboxing. 





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