Untested, but it usually works, and written in a way that if this is homework, someone will notice. 
sub slurp { local *ARGV; @ARGV = @_; <> }

my %where;

$where{$_} .= "1" for slurp($file1);
$where{$_} .= "2" for slurp($file2);

for (sort keys %where) {
  my $where = $where{$_};
  if ($where =~ /12/) {
    print "both";
  } elsif ($where =~ /1/) {
    print "left";
  } else {
    print "right";
  }
  print ":\t$_";
}

[download]

-- Randal L. Schwartz, Perl hacker

update: Yeah, oops, thanks akho. Fixed.

In reply to Re: Comparing 2 files without diff or compare by merlyn
in thread Comparing 2 files without diff or compare by ilottl

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