How can I "peek" at the keyboard without suspending?

[Jeffrey Hiess]

Something like getchar() doesn't work, since it "waits" for input.


#include <stdio.h>
while (1)
{
if (getchar()) /* break if any key is pressed */
{
break;
}

/* lot's of other code goes here */
}

 

[Andreas Kahari]

Something like getchar() doesn't work, since it "waits" for input.

Read this FAQ:

http://www.eskimo.com/~scs/C-faq/q19.1.html

 

[Dan Pop]

Something like getchar() doesn't work, since it "waits" for input.

Ever considered reading the FAQ *before* posting?

Dan

 

[Irrwahn Grausewitz]

Read this FAQ:

http://www.eskimo.com/~scs/C-faq/q19.1.html

To OP: in future please cross-post your message instead of
multi-posting. Your question has already been answered in
alt.comp.lang.learn.c-c++. Thank you.

Regards

 

[Jeffrey Hiess]

Ever considered reading the FAQ *before* posting?

Dan

Did I miss something? Which FAQ? Please expound. I'm posting from
Google Groups.

On the topic of the original post, I am hesitant to write platform
specific code to avoid suspending. Instead, I was pondering the idea
of forking a sub process which would call getchar() (and suspend) and
then main process could monitor the sub process for a signal to take
action. My multi-threading coding skills are a bit rusty, but it seems
like this would work.

 

[Keith Thompson]

(e-mail address removed) (Dan Pop) wrote in message


Did I miss something? Which FAQ? Please expound. I'm posting from
Google Groups.

On the topic of the original post, I am hesitant to write platform
specific code to avoid suspending. Instead, I was pondering the idea
of forking a sub process which would call getchar() (and suspend) and
then main process could monitor the sub process for a signal to take
action. My multi-threading coding skills are a bit rusty, but it seems
like this would work.

Forking and monitoring other processes are at least as system-specific
as checking for pending keyboard input.

 

[Morris Dovey]

On the topic of the original post, I am hesitant to write platform
specific code to avoid suspending. Instead, I was pondering the idea
of forking a sub process which would call getchar() (and suspend) and
then main process could monitor the sub process for a signal to take
action. My multi-threading coding skills are a bit rusty, but it seems
like this would work.

Jeffrey...

It sounds like might be a good place to
ask this question. If you have access to "Advanced Programming in
the UNIX Environment" by Richard Stevens, you might find it
helpful. You might find http://www.iedu.com/mrd/c/getch.c
(written with help from APUE to run under Linux) interesting.

Note that your code will (necesarily) be less portable than a
standard-compliant program that uses getchar() - the price for
being just a bit chummier with the operating system.

 

[Gordon Burditt]

On the topic of the original post, I am hesitant to write platform

specific code to avoid suspending.

You have no choice. ANSI C does not provide non-blocking I/O.

Instead, I was pondering the idea
of forking

^^^^^^^
PLATFORM-SPECIFIC

a sub process

^^^^^^^^^^^
PLATFORM-SPECIFIC

which would call getchar() (and suspend) and
then main process could monitor

^^^^^^^
If this is anything but setting up a signal handler, this is PLATFORM-SPECIFIC

the sub process

^^^^^^^^^^^
PLATFORM-SPECIFIC

for a signal to take

^^^^^^^^^^^^
sending a signal to another process is PLATFORM-SPECIFIC.

action. My multi-threading coding skills are a bit rusty, but it seems

^^^^^^^^^^^^^^^
Multi-threading except for the skimpy support for signal handlers in C
is PLATFORM-SPECIFIC.

like this would work.

Gordon L. Burditt

 

[Richard Bos]

Did I miss something? Which FAQ? Please expound. I'm posting from
Google Groups.

That is frequently an explanation, but never an excuse.

Richard

 

[Christopher Benson-Manica]

Did I miss something? Which FAQ? Please expound. I'm posting from
Google Groups.

Since no one else seemed to be clear, yes, you did miss something -
the FAQ located at http://www.eskimo.com/~scs/C-faq/top.html.

 

[Ian Bell]

Since no one else seemed to be clear, yes, you did miss something -
the FAQ located at http://www.eskimo.com/~scs/C-faq/top.html.

There seems to be no downloadable version of the full latest FAQ.

Ian

 

[Irrwahn Grausewitz]

There seems to be no downloadable version of the full latest FAQ.

Follow the link on http://www.eskimo.com/~scs/C-faq/top.html to
http://www.eskimo.com/~scs/C-faq/versions.html and from there to
ftp://ftp.eskimo.com/u/s/scs/C-faq/faq.Z.

Or try: http://www.faqs.org/faqs/C-faq/faq/index.html (~280K).

HTH

Regards