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I'm studying Window Sockets in C and writing a multiplexing i/o client-server application I'm tryting to deal with Standard Threads. I want to checkactivity in
stdin, stdout and stderr
but It seems I can't get how it works. Input thread it's, for example, when I use printf function or open some file (fopen,fopen_s), output - reading a message from serverby client, reading strings from fileand errorthread -just checking of errors (using fprintf(errno, "param2", param3).

What I have tried:

I want to check activity of this Threadsand I'm writing a programm just to see how it works but I met some issus.I don't understand how to check this activity (yes, maybe it soundsstupid but I really stucked with that).

I wanna do that using select() function and then FD_ZERO and FD_SET. How should I get which socket is active and which is not? How to make themactive?

Here is my "scelet" code:
<pre>	#pragma comment(lib, "ws2_32.lib")
	#include <winsock2.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <errno.h> 
	#include <sys/types.h>

	#define BUFFERSIZE 64
	#define PORT 3765
	#define SERVERADDR argv[1]

	int main(int argc, char *argv[])
		struct sockaddr_in serverAddr = { 0 };
		fd_set readSD;
		fd_set writeSD;
		fd_set errorSD;
		timeval tv;
		int retVal;
		char msg = '1';
		FD_SET(msg, &readSD);
		FD_SET(msg, &writeSD);
		FD_SET(msg, &errorSD);
		tv.tv_sec = 5;
		retVal = select(msg + 1, &readSD, &writeSD, &errorSD, &tv);
		if (retVal < 0)
			return -1;
		else if (retVal == 0)
			printf("There is nobody, sorry\n");
			int fd_isset_r = FD_ISSET(msg, &readSD);
			if ((fd_isset_r)!=0)
				printf("fd_isset_r error\n");
				printf("readSD is %s \n", FD_ISSET(msg, &readSD) ? "ready" : "not ready");

			int fd_isset_w = FD_ISSET(msg, &writeSD);
			if ((fd_isset_w) != 0)
				printf("fd_isset_w error\n");
				printf("writeSD is %s\n", FD_ISSET(msg, &writeSD) ? "ready" : "not ready");

			int fd_isset_er = FD_ISSET(msg, &errorSD);
			if ((fd_isset_er) != 0)
				printf("fd_isset_er error\n");
				printf("errorSD is %s\n", FD_ISSET(msg, &errorSD) ? "ready" : "not ready");
		return 0;

I aprreciate any advices and help. Thanks
Updated 25-Apr-17 5:46am

1 solution

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Solution 1

For learning client/server architecture you better read this article or watch that video. This gives you better insight of real life client/server programming.

The standard I/O are system constants which are working with the PC hardware and working on the FIFO principle.
GeorgeZv 27-Apr-17 16:17pm
Thank you! I found this article very useful

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