use strict; use warnings;

my $title  = " A   B    C   D\n";
my $format = "%2d  %2d   %2d  %2d\n";

print $title;
printf $format , @{ $_ } for fetch_data();

sub fetch_data
{
  my @data;
  while ( my $line = <DATA> )
  {
    next
      if $line =~ m/^\s*#/
      or $line =~ m/^\s*$/
      ;

    push @data
      , [ map get_standin( $_ ), split /;/ , $line , 4 ];
  }
  return @data;
}

sub get_standin
{
  my ( $in ) = @_;

  my $standin = 0;

  return $standin unless defined $in;

  for ( $in )
  {
    s/^\s+//;
    s/\s+$//;
  }
  return length $in ? $in : $standin;
}

__DATA__
#  Data (say 2 digit numbers at most, or missing).

1; 2 ; 3; 5
9;97; ;0

;  6 ; 8 ;

;;; 76