将timeval转换为time_t

Question

如何将timeval转换为time_t？我正在尝试转换： umtp-＆gt; ut_tv到time_t所以我可以使用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只存储秒数，所以

 time_t time = (time_t)ut_tv.tv_sec;

应该有效，但由于你只是在寻找差异，所以总有减法的魔力。

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

这使您可以保持以前的所有精确度。

Answer 2

不使用c-cast，您只需执行此操作：

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