Thank you for yor help, but there are still some things I didn't understand...so this is my code: 

#!/usr/bin/perl
use warnings;
use strict;

sub process_file
{
  my ($original, $final) = @_;
  open( my $original_fh, "<", $original ) or die $!;
  open( my $final_fh,    ">", $final )    or die $!;

  my $first = <$original_fh>;
  print $final_fh $first;
  my @replace = $first =~ /"([^"]*)"/g;

  while (my $line = <$original_fh>) {
    print "Enter the desired number of columns: ";
          my $nr = <STDIN>;
          chomp($nr);
    $line =~ s/((\w\w\t){$nr})/$1\n/g;
    $line =~ s/\t/,/g;
    $line =~ s/(\d{2})/$replace[$1]/g;
    print $final_fh $line;
  }

  close $original_fh;
  close $final_fh;
}
my @files = glob '*.bit';
for my $name (@files) {
  my $new_file = $name =~ s/bit$/csv/r;
  process_file($name, $new_file);
}

[download]

so I used glob to fill @files, the statement to ask the user has to be in the while loop so it can transform the files by the number entered(after I finish the working code I will make it more robust and cautious) and the source for read and output for write are opened so I don't think I have to open them again. Do you have any advice for my specific code so I can finally understand? Thank you for your effort!

In reply to Re^6: Read from multiple files change the data with a script and the write the respective output files with a different extension -- plain english by Akatsuki
in thread Read from multiple files change the data with a script and the write the respective output files with a different extension by Akatsuki

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