将timeval转换为time_t

Question

How do I convert timeval to time_t? I'm trying to convert: umtp->ut_tv to a time_t so I can use a difftime(a,b).

struct {
   int32_t tv_sec;         /* Seconds */
   int32_t tv_usec;        /* Microseconds */
           } ut_tv;                    /* Time entry was made */
 struct timeval ut_tv;      /* Time entry was made */

Answer 1

time_t just stores seconds, so

 time_t time = (time_t)ut_tv.tv_sec;

Should work, but since you're just looking for a difference, there's always the magic of subtraction .

struct timeval diff = {a.tv_sec-b.tv_sec, a.tv_usec-b.tv_usec};

This lets you keep all the precision you had before.

Answer 2

Without using c-cast, you can simply do this :

struct timeval rawtime_s_us;
gettimeofday( &rawtime_s_us, NULL );
time_t rawtime_s = rawtime_s_us.tv_sec;