Mutate the Ns first:

use strict;
use warnings;
use Data::Dumper;

my $s1 = "STCATTNNNSATCGCT";
my $s2 = "ATCGTCGSNNNNATCG";
$s1 =~ tr/N/n/;
my $merge = $s1 ^ $s2;
my $count = $merge =~ tr/\0//;

print $count;

[download]

Prints:

4

[download]
Perl is Huffman encoded by design.

In reply to Re: Conditional Bitwise XOR(^) Operator in Matching Chars Count of Two Strings by GrandFather
in thread Conditional Bitwise XOR(^) Operator in Matching Chars Count of Two Strings? by monkfan

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