Richard Heathfield wrote:
> Hal Vaughan said:
>
>> I have a series of codes that will include NULL bytes
>
> Shhhhh, we're trying to sleep... NULL is a pointer. You mean null bytes,
> right? i.e. '\0' rather than ((void *)0)
My bad. Many, many years ago (in the 1980s) I used to program in
Assembler
(VAX 11/780 and 6502) and then didn't program for over a decade, then used
basically Perl and Java. I'm still getting used to thinking more like
Assembler than like higher level languages. It takes a while to adjust.
>> and other non-text
>> data that I need to send to a device through a file.
>
> Not a problem.
>
>> Since a NULL terminates a string, how do I send a string containing
NULL
>> bytes to a file (or device, depending on the OS)?
>
> Don't use strings. For example, here's one way to send the bytes 00, 9E,
> 3A, 00, 00, 5F, CD, and FE to a file:
>
> unsigned char buf[8] = { 0x00, 0x9E, 0x3A, 0x00, 0x00, 0x5F, 0xCD, 0xFE
};
> fwrite(buf, sizeof buf / sizeof buf[0], sizeof buf[0], fp);
Okay, got it. Just to be sure, fp is filepointer, the same as an int file
descriptor, right? (I know there are different ways of opening files and
I'm still getting used to this and realize there's a lot I don't know.)
> Now let's send eight straight zeros to the same stream:
>
> memset(buf, 0, sizeof buf / sizeof buf[0]);
> fwrite(buf, sizeof buf / sizeof buf[0], sizeof buf[0], fp);
>
> Now let's send a zero and three letter 'N's:
>
> buf[0] = '\0'; /* not really necessary since we did it a couple of lines
> up */
> buf[1] = buf[2] = buf[3] = 'N';
> fwrite(buf, 4, sizeof buf[0], fp);
>
> See? It's easy really. Just stop thinking in terms of strings, and think
> in terms of raw data instead.
Okay. Like I said, I am trying to get used to thinking more like I used
to
many, many eons ago when I used Assembler.
Thanks for the help!
Hal
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