Multiplexing Multiple Clients (Cont)

Here is how to use 'select':
 #include <sys/time.h>   /* 'struct timeval'.       */
 #include <sys/types.h>  /* fd_set and its macros.  */
 #include <sys/unistd.h> /* 'select'.               */

 fd_set rfd;   /* file descriptors to read from.    */
 int s1, s2;   /* socket file descriptors.          */
 struct timeval timeout; /* time to wait in select. */
 int rc;

 /* store our file descriptors in the given set.    */
 FD_ZERO(&rfd);
 FD_SET(s1, &rfd);
 FD_SET(s2, &rfd);
 /* prepare to wait up to 10 seconds. */
 timeout.tv_sec = 10; timeout.tv_usec = 0;
 rc = select(max(s1, s2), &rfd, NULL, NULL, &timeout);
 if (rc > 0) { /* we got some input. */
     if (FD_ISSET(s1, &rfd)
         ...    /* there's input on descriptor 's1'. */
     if (FD_ISSET(s2, &rfd)
         ...    /* there's input on descriptor 's2'. */
 }