Hello everyone,
I'm trying to build a socket class that works similar to the visual basic win_sock.
Is it possible in c++ to know if a data has arrived to the socket? Like interrupt or event?

How do I know that I received something like the VB. In VB if Data is arrived the function Data_arrival is called. Can I do this in C or C++?


Thank you
alaa

You can make a new thread in your program which calls the select() system call to wait for data on the socket. I vaguely recall select() being able to have a timeout so you could, rather than use a separate thread, simply periodically poll the socket for new data.

Ask more questions.

-pcweirdo.

Moved: This thread is more suitable in Programming and has been moved accordingly to help your thread/question get the exposure it deserves.

pcweirdo is right: if you're on Linux, "select()" what you want to look at:
http://www.lowtek.com/sockets/select.html

Book recommendation:
Unix Network Programming, 3rd Edition, W. Richard Stevens, Andrew M. Rudoff
http://www.bookpool.com/sm/0131411551
<= *THE* BOOK ON SOCKETS; MUCH EXCELLENT DETAIL ON EVERYTHING
YOU'LL NEED/WANT TO KNOW ... INCLUDING "SELECT()"

Thanks guys. select workd perfectly, here is an example of what i did:

#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
int
main(void) {
fd_set rfds;
struct timeval tv;
int retval;
/* Watch stdin (fd 0) to see when it has input. */
FD_ZERO(&rfds);
FD_SET(0, &rfds);
/* Wait up to five seconds. */
tv.tv_sec = 5;
tv.tv_usec = 0;
retval = select(1, &rfds, NULL, NULL, &tv);
/* Don’t rely on the value of tv now! */
if (retval)
printf("Data is available now.\n");
/* FD_ISSET(0, &rfds) will be true. */
else
printf("No data within five seconds.\n");
return 0;
}

Cool - we're glad we could help.

One design caveat - please always remember the mantra:

Polling is Bad

That is, you want to structure your "main event loop" so that it blocks - FOREVER - until input arrives. You do NOT (if you can at all help it) have a design where you periodically check whether or not anything has happened.

In your coding please always regard a timeout as a "yellow flag" and ask yourself if you can restructure things so that you DON'T need to time out and you DON'T have to incur the overhead of "checking anything".

IMHO .. PSM

Bookmark this thread. Nobody will ever, ever say those words on this internet again.

allomeen I barely comprehend what you've done there but I salute you. Keep up the good work, and remember the code tags to preserve leading spaces.

-pcweirdo.