You can get the information back from the strings if needed:
use warnings;
use strict;

my $source="ATTCCGGG";
print "source: $source\n";
for my $str ( "ATTGCGGG", "ATACCGGC", "ACTGCGGT" , "ATCGGGGG" ) {
    print "string: $str\n";
    my @res = unpack "c*", $source ^ $str;
    for my $i (grep $res[$_], 0 .. $#res) {
        print "$i: ", substr($source, $i, 1), "->",
            substr($str, $i, 1), "\n";
    }
}

[download]
I am not sure how fast this is compared to the PDL solution.

In reply to Re^5: mismatching characters in dna sequence by choroba
in thread mismatching characters in dna sequence by prbndr

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