Test running time in Linux

/*This program is for testing the running time of for cycle.*/

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

int main()
{
int i;
long int time;
struct timeval time_start;
struct timeval time_end;

gettimeofday((struct timeval*)&time_start,NULL);
for(i=0;i<10000;i++);
gettimeofday((struct timeval*)&time_end,NULL);
time=time_end.tv_usec-time_start.tv_usec;
printf("The running time of cycle is %d us",time);
}