#comma delimited user input
@words = split(/,/, $words);
#copy of array for later
@words2 = @words;



open FH, "$data" or die "Can't open $data: $!";
flock (FH, 1) or die "Can't lock $data for reading: $!";
my @all = <FH>;
close FH;

#iterate through user input comparing with db
while (@words) {
my $item = shift (@words);
$count++;


	foreach my $line (@all) {
	($one,$two,undef,$four,$spare_1,$spare_2) = split "\t",$line;
		chomp;
		if ($item eq "$four") { 
		push (@matched, $item);
		push (@counted, $count);
		last;
		}
	}
}

#iterate through @counted applying undef to matched items in copy of user input array
while (@counted) {
	my $item = shift (@counted);
	$words2[$item -1] = undef;
	}

#remove undef items from user input leaving only unmatched items.
foreach my $item (@words2) {
	unless ($item eq "") {
		push (@uniq, $item);
	}
}		

#@matched contains only matched items
#@uniq contains only unmatched items