struct timeval 和 struct timespec

timeval   DESCRIPTION   The functions gettimeofday and settimeofday can get and set the time as   well as a timezone. The tv argument is a timeval struct, as specified in <sys/time.h>:        struct timeval {         time_t tv_sec; /* seconds */         suseconds_t tv_usec; /* microseconds */   };         其中返回的timeval值为Epoch(00:00:00 1970-01-01 UTC)到创建struct timeval时的时间,tv_sec为秒数部分,tv_usec为微秒数部分(10的-6次方秒)。比如当前程序运行的tv_sec为1244770435,tv_usec为442388,即当前时间距Epoch时间1244770435秒,442388微秒。测试代码如下:   #include