시간 측정을 위한 gettimeofday 사용예제

#include <sys/time.h>
#include <unistd.h>
struct timeval
{
    long tv_sec;       // 초
    long tv_usec;      // 마이크로초
}
int gettimeofday(struct timeval *tv, struct timezone *tz);


long gettimeofday_d(void)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (tv.tv_sec*1e6) + tv.tv_usec;
}


long getTimeGap(struct timeval *s_t, struct timeval *e_t)
{
    struct timeval rt;
    long et = 0L;

    rt.tv_sec = e_t->tv_sec - s_t->tv_sec;
    rt.tv_usec = e_t->tv_usec - s_t->tv_usec;

    if(rt.tv_usec < 0)
    {
        rt.tv_sec--;
        rt.tv_usec += 1000000L;
    }
    et = (rt.tv_sec*1000000L) + rt.tv_usec;
    return et;
}