Thanks. You caught me!

Here are some idioms that could be preferable:

use strict;
use warnings;

my @data = qw(foozbar foozball zoobeezoobedo);


my $acc = 0;
do {
    my $count = s/o/*/g;
    $acc+=$count;
} for @data;
print "$acc\n";


# But the above really can just boil down to:
my $count;
$count += s/\*/o/g for @data;
print "$count\n";


# List::Util's reduce is always fun.
use List::Util 'reduce';

my $total = reduce {$a += $b =~ s/o/*/g} 0, @data;
print "$total\n";
[download]

Hope this helps (and thanks again for catching the error).