How to set up time out for client program written in C

Take a look here for more info (it's part of Beej's guide to network programming, which is a recommended read !) :

        http://www.beej.us/guide/bgnet/output/html/singlepage/bgnet.html#select

fprintf(perr, "\nSending the message.... %s", msg); /* send the message */
if( send(sock_id, msg, sizeof(msg), 0) < 0 ) {
fprintf(perr, "\nFailed to send data to widget#2.");
fclose(perr);
exit(5);
}

????? BETWEEN SEND AND RECV Function I want to set up TIME- OUT  ???


/* Receive the echoed message from the Widget#2 */
if( recv(sock_id, msg, sizeof(msg), 0) < 0 ) {
fprintf(perr, "\nFailed to receive data from widget#2.");
fclose(perr);
exit(6);
}
printf("The message from the server was: %s\n", msg);

>????? BETWEEN SEND AND RECV Function I want to set up TIME- OUT  ???
Time out implies that there is an operation that times out. What operation are you performing between send and recv?

If you meant simply wait for a specific period of time, then use either nanosleep() in case you want to sleep while waiting or alarm() in case you wish to work on something else while waiting.

If you actually meant recv timeout then use select as has already been suggested.
Another option for timing out is to use setsockopt() with SO_RCVTIMEO option. Check man page on your system to verify if this option has been implemented in your platform.
http://linux.die.net/man/3/setsockopt

//Example from select man page
#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 == -1)
        perror("select()");
    else 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;
}

                                              

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>> ????? BETWEEN SEND AND RECV Function I want to set up TIME- OUT  ???

As I said : take a look at select. That function is used for timeouts when dealing with receiving data. You can find code samples and more explanation in the second link I posted.

I have created the socket ( sock_id)......
Now after this and before connect() ( see below ..connect, send and recv ) I want to set up time out for 30 seconds for example..

>>>>>>>>>
??? Set up time out here
SAY ..If I don't receive anything from the server which I am checking in the last block, then I should be message: timed out.. ??????



if( connect(sock_id, (struct sockaddr *)&client, sizeof(client)) < 0) {
fprintf(perr, "Error: Failed to connect to widget#2.\n");
fclose(perr);
exit(4);
}
else
fprintf(perr, "Connection to widget#2 successful.\n");


fprintf(perr, "Sending the message.... %s\n", msg); /* send the message */
if( send(sock_id, msg, sizeof(msg), 0) < 0 ) {
fprintf(perr, "Error: Failed to send data to widget#2.\n");
fclose(perr);
exit(5);
}

/* Receive the echoed message from the Widget#2 */
if( recv(sock_id, msg, sizeof(msg), 0) < 0 ) {
fprintf(perr, "Error: Failed to receive data from widget#2.\n");
fclose(perr);
exit(6);
}
printf("The message from the server was: %s\n", msg);

>>>>>