my $output='$std | dot |$data| dot '."\n";

while(<>) {
	my $std = $_;
	my $std_dot = $.;

	my $data = <DATA>;
	my $data_dot = $.++;

	chomp $std;
	chomp $data;

	last if $std eq '.';

	$output.=sprintf "%4s |%4s |%4s |%4s\n",
		$std, $std_dot, $data, $data_dot;
}

print $output;
__DATA__
a
b
c
d
e

##</code><code>##

a
b
c
d
e
.
$std | dot |$data| dot
   a |   1 |   a |   1
   b |   2 |   b |   3
   c |   3 |   c |   5
   d |   4 |   d |   7
   e |   5 |   e |   9

##</code><code>##

my $output='$std | dot | $r1 |$data| dot | $r2 '."\n";

while(<>) {
	my $std = $_;
	my $std_dot = $.;

	my $data = <DATA>;
	my $data_dot = $.++;

	chomp $std;
	chomp $data;
	my ($r1, $r2);

	if(
		($r1 = $data =~ /a/ .. $data =~ /e/) &&
		($r2 = $std =~ /a/ .. $std =~ /e/)
	) {
		$output.=sprintf "%4s |%4s |%4s |%4s |%4s |%4s \n",
			$std, $std_dot, $r1, $data, $data_dot, $r2;
	} else {
		last;
	}
}

print $output;
__DATA__
a
b
c
d
e

##</code><code>##

a
b
c
d
e
f
$std | dot | $r1 |$data| dot | $r2
   a |   1 |   1 |   a |   1 |   1
   b |   2 |   2 |   b |   3 |   2
   c |   3 |   3 |   c |   5 |   3
   d |   4 |   4 |   d |   7 |   4
   e |   5 | 5E0 |   e |   9 | 5E0