Linux系統下精確到微秒級的時間操作函數

#include <sys/time.h>
#include <stdio.h>
#include <math.h>

void function()/*用來耗用一定的時間而已，無實際用處的函數*/
{
  unsigned int i,j;
  double y;
  for(i=0;i<10000;i++)
    for(j=0;j<10000;j++)
      y=sin((double)i);
}

int main(int argc, char ** argv)
{
  struct timeval tpstart,tpend;
  float timeuse;

  gettimeofday(&tpstart,NULL);
  function();
  gettimeofday(&tpend,NULL);
  timeuse=1000000*(tpend.tv_sec-tpstart.tv_sec)+tpend.tv_usec-tpstart.tv_usec;
  timeuse/=1000000;
  printf("Used Time:%fn",timeuse);
  exit(0);
}

struct timeval {
               long tv_sec;        /* seconds */
               long tv_usec;  /* microseconds */
       };