my @substrings;
{
    my $size = 10;
    no warnings 'substr';
    push @substrings, substr($string, 0, $size, '')
        while $string;
}

##</code><code>##

my @substrings = do {
    local $/ = \10;
    open my $fh, '<', \$string;
    <$fh>
};