howto grab key strokes directly?

[C.Hagedorn]

ups, ok hier nochmal auf deutsch:



Wie veranlasse ich mein C Programm dazu direkt auf Tastendruecke zu
reagieren?

Standardmaessig wird das doch (soweit ich weiss) in einem
Line-Puffer zwischengepseichert. Erst mit <return> bemerkt
select() etwas am Eingang. Ich moechte aber beispielsweise direkt
in einer Endlos-Schleife mitbekommen, wenn Ctrl-q gedrueckt wurde.

Wie mache ich das?

Nach welchen Schlagworten muss man da eigentlich suchen?
Kann man einfach so den Standard Modus von stdin aendern und kurz vor
Programmende wieder herstellen oder gibt es da Komplokationen?

Vielen Dank schonmal,
Christoph

[Raymundo M. Vega]

there must be several ways of doing this, here is one:

- in your program include <termio.h>
- have a statmement: struct termio save, term;
- use ioctl to read terminal settings into term structure
- save a copy of term into save structure
- term.c_lflag&= ~ICANON;
- term.c_cc[VMIN] = 1;
- term.c_cc[VTIME] = 0;
- set nbew state with new call to ioctl(0, TCSETA, &term);
- your loop follows here, reading one char from stdin each time:
read(0, &in, 1);
where in is a char variable.
- process every input
- when loop is broken then reset old state with:
ioctl(0, TCSETA, &save);

It may help.

raymundo

C.Hagedorn wrote:

> Hi all,
>
> i want to write a console application with an infinite loop, which
> reacts on key strokes like Ctrl-q for example to end the loop .
>
> How can i do this?
>
> I figured out to use select() to get noticed if stdin has data to read,
> but i still have to press Enter to confirm the input.
>
> How can i set stdin again within my application to get
> unbuffered, non-blocking (no suspend of the process) input?
>
> The select() function is a good step, but how to switch off <cr>?
>
> Thanks in advance,
> Christoph
>
>

[Floyd Davidson]

[email]mdanko@tesla.rcub.bg.ac.yu[/email] (Darko M.) wrote:

>Wow! This is really something. Is it yours or did you pick it up in
>some header? I the answer is "It's mine" then please tell me where's
>all the terminals' stuff documentation, because it definitely isn't in
>Stevens (not that much).
>
>It would be a really precious information, thank you.

I've been posting that to Usenet for well over a decade. It has
evolved significantly because it originally used termio and
pre-dated ANSI C, but since about 1993 has used termios.
Actually, that particular version has modifications that were
not in it the last time I posted it. I changed all uses of file
descriptor 0 to use STDIN_FILENO instead, and reformatted it
eliminate lines longer than 64 characters. There are a couple
of other changes that I'm thinking of, which might be made the
next time it is posted.

I believe, but have not verified, that virtually everything
needed to understand what it does is in fact in Stevens, though
it might be spread around in too many different places to be
obvious. That is why I've bundled it with an example "menu
program" as a demo.

Other sources of information are also spread out. The man pages
for stty, termios, and each function used in the program should
all be read. The C FAQ and the FAQ for this newsgroup are also
required reading.

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) [email]floyd@barrow.com[/email]

[Morris Dovey]

C.Hagedorn wrote:

> Hi all,
>
> i want to write a console application with an infinite loop, which
> reacts on key strokes like Ctrl-q for example to end the loop .
>
> How can i do this?
>
> I figured out to use select() to get noticed if stdin has data to read,
> but i still have to press Enter to confirm the input.
>
> How can i set stdin again within my application to get
> unbuffered, non-blocking (no suspend of the process) input?
>
> The select() function is a good step, but how to switch off <cr>?

Christoph

Take a quick look at [url]http://www.iedu.com/mrd/c/getch.c[/url] for a
program written with info from Stevens' "Advanced Programming in
the UNIX Environment".

HTH
--
Morris Dovey
West Des Moines, Iowa USA
C links at [url]http://www.iedu.com/c[/url]