Weather update client in C

// Weather update client
// Connects SUB socket to tcp://localhost:5556
// Collects weather updates and finds avg temp in zipcode

#include "zhelpers.h"

int main (int argc, char *argv [])
{
// Socket to talk to server
printf ("Collecting updates from weather server…\n");
void *context = zmq_ctx_new ();
void *subscriber = zmq_socket (context, ZMQ_SUB);
int rc = zmq_connect (subscriber, "tcp://localhost:5556");
assert (rc == 0);

// Subscribe to zipcode, default is NYC, 10001
char *filter = (argc > 1)? argv [1]: "10001 ";
rc = zmq_setsockopt (subscriber, ZMQ_SUBSCRIBE,
filter, strlen (filter));
assert (rc == 0);

// Process 100 updates
int update_nbr;
long total_temp = 0;
for (update_nbr = 0; update_nbr < 100; update_nbr++) {
char *string = s_recv (subscriber);

int zipcode, temperature, relhumidity;
sscanf (string, "%d %d %d",
&zipcode, &temperature, &relhumidity);
total_temp += temperature;
free (string);
}
printf ("Average temperature for zipcode '%s' was %dF\n",
filter, (int) (total_temp / update_nbr));

zmq_close (subscriber);
zmq_ctx_destroy (context);
return 0;
}