Kristou Says

// returns the number of usecs of (t2 - t1)
long time_elapsed (struct timeval &t1, struct timeval &t2) {

long sec, usec;

sec = t2.tv_sec - t1.tv_sec;
usec = t2.tv_usec - t1.tv_usec;
if (usec < 0) {
--sec;
usec = usec + USEC_PER_SEC;
}
return sec*USEC_PER_SEC + usec;
}

struct timeval start_time;
struct timeval end_time;
void start_timer() {
struct timezone tz;
gettimeofday (&start_time, &tz);
}
long end_timer() {
struct timezone tz;
gettimeofday (&end_time, &tz);
return time_elapsed(start_time, end_time);
}