use strict;
use warnings;


my $filename = "file1.txt";
my $filename2 = "file2.txt";
my $logger = "log.txt";
my %seen;
my @unique;
my @strings;
my %seen2;
my @unique2;
my @strings2;
my $handle2;
my $s;
my $s2;
my $seen;
my $seen2;
my $line2;


open my $handle, '<', $filename || die "$0: Can't open $filename for reading: $!";

open my $FH, '>', $logger || die "$0: Can't open $logger for writing: $!";




while (my $line = <$handle>) {
	my @strings = $line =~ m/(RC[0-9][0-9][0-9][0-9])/;



		foreach my $s ( @strings ) {
			next if $seen{ $s }++;
			push @unique, $s;
			print $FH "@strings\n";  # push output to file log.txt for testing
			


    }
	
	}
	
close $FH or die $!;

##</code><code>##

use strict;
use warnings;


my $filename2 = "file2.txt";
my %seen2;
my @unique2;
my @strings2;
my @line2;



open my $handle2, '<', $filename2 || die "$0: Can't open $filename2 for reading: $!";




while (my $line2 = <$handle2>) {
	my @strings2 = $line2 =~ m/(RC=[0-9][0-9][0-9][0-9])/;


	
	foreach my $s2 (@strings2) {



		foreach my $s2 ( @strings2 ) {
        next if $seen2{ $s2 }++;
        push @unique2, $s2;
		print "$line2\n";
    }
	
	}
}