use Modern::Perl;

my @patterns = qw/GAATTC CCWGG/;

while ( my $sequence = <DATA> ) {
    my @matches;
    while ( $sequence =~ m/($patterns[0]|$patterns[1])/g ) {
        for my $expr ( 1 .. $#- ) {
            push @matches, $-[$expr] .. $+[$expr] - 1;
        }
    }
    say "@matches";
}

__DATA__
GAATTCACGGATAGCCWGGTACGATGATAGATGAATTCGACTAGAATGCCWGGAAGAATgGAATTC
GAATTCACGGATAGCCWGGTACGATGATAGATGAATTCGACTAGAATGCCWGGAAGAATgGAATTC
GAATTCACGGATAGCCWGGTACGATGATAGATGAATTCGACTAGAATGCCWGGAAGAATgGAATTC

##</code><code>##

0 1 2 3 4 5 14 15 16 17 18 32 33 34 35 36 37 48 49 50 51 52 60 61 62 63 64 65
0 1 2 3 4 5 14 15 16 17 18 32 33 34 35 36 37 48 49 50 51 52 60 61 62 63 64 65
0 1 2 3 4 5 14 15 16 17 18 32 33 34 35 36 37 48 49 50 51 52 60 61 62 63 64 65