Problem converting a text file into binary file using perl

Question

I would like to convert some data in binary using Perl. The data needs to be output in 8 bits binary. The original data comes in this format:

To do so, I transformed the data to suppress the ".0000" then I use the pack function with the option C* (this format correspond to an "unsigned character (usually 8 bits)" according to the documentation). I called this file txt2bin.pl:

my $file = $ARGV[0];
my $fileout = $file.".bin";

if($file eq "-h" or $file eq "-help" or $file eq "")
{  
    print "Usage : txt2bin.pl file_in\n";
    print "        file_out = file_in.bin\n";
    print "This script converts a txt file to a binary file\n";

}

else
{
  print "File in = $file\n";
  print "File out = $fileout\n";

  open(FILE,"<$file") or die $!;
  open(FILEOUT,">$fileout") or die $!;
    binmode FILEOUT;
    while(defined(my $line=<FILE>))
    {
      chomp($line);
      $line =~ s/\.0000//;
      syswrite FILEOUT, pack("C*",$line);
    }
  close(FILE);
  close(FILEOUT);
}

I also need to be able to do the reverse operation, so, I created another file bin2txt.pl:

my $file = $ARGV[0];
my $fileout = $file.".txt";

if($file eq "-h" or $file eq "-help" or $file eq "")
{
    print "Usage : bin2txt.pl file_in\n";
    print "        file_out = file_in.txt\n";
    print "This script converts a binairy file to a txt file\n";
}

else
{
  print "File in = $file\n";
  print "File out = $fileout\n";

  my $file = "<$file";

  # undef $/ to read whole file in one go
  undef $/;

  open(FILE,$file) or die $!;
  open(FILEOUT,">$fileout") or die $!;

  # binmode FILE to supress conversion of line endings
  binmode FILE;

  my $data = <FILE>;
  $data =~ s/(.{1})/unpack("C*",$1).".0000 \n"/eg;
  syswrite FILEOUT, $data;
}

However, when I execute the first program txt2bin.pl, then the second, I should get:

Instead, of that, I get this:

The 10.0000 does not show up, do you guys have any idea about this ? Thanks for helping.

Probably the 10 is taken as a new line character 0x0a somehow? — Håkon Hægland
– Håkon Hægland, Commented Jun 19, 2019 at 13:28
@HåkonHægland, but why is it the only one ? And how to prevent that ? — dalex78
– dalex78, Commented Jun 19, 2019 at 13:36
I know, in other part of my code (not shown above), I have {3}, for more genericity, I keept the {1}. Thanks for the remarks anyway :-) — dalex78
– dalex78, Commented Jun 20, 2019 at 15:11

Håkon Hægland · Accepted Answer · 2019-06-19 13:36:46Z

2

You need to add the s modifier to the regexp substitution in order to match a 10 (newline) :

$data =~ s/(.{1})/unpack("C*",$1).".0000 \n"/seg;

From perldoc perlre :

s
Treat the string as single line. That is, change "." to match any character whatsoever, even a newline, which normally it would not match.

answered Jun 19, 2019 at 13:36

Håkon Hægland

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