C语言Linux时间操作

#include <sys/time.h>
#include <stdio.h>
#include <math.h>
void function()
{
unsigned int i,j;
double y;
for(i=0;i<1000;i++)
    for(j=0;j<1000;j++)
y=sin((double)i);
}
main()
{
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: %f\n",timeuse);
exit(0);