return @retary, $count;

##</code><code>##

    return $count, @retary;
    ...
    ($count, @ary1) = read_data(...);

##</code><code>##

    return \@retary, $count;
    ...
    ($ary1, $count) = read_data(...);

##</code><code>##

    @ary1 = read_data(...);
    $num = @ary1;
OR
    $ary1 = read_data(...);
    $num = @$ary1;