while( $line =~ /\G(.)/g )
{
    my $this_char = $1;
    ++$char_in_line;

    my $ascii = ord $this_char;
    if( ( $ascii < 32 || $ascii > 126 ) && $ascii != 0 )
    {
         ++$total_bad_chars{$ascii};
         printf "filename: %s -- line_n: %d -- char_in_line: %4d -- ascii: %4d\n",
             $filename, $line_n, $char_in_line, $ascii;
    }
}