#include <time.h>
#include <stdio.h>
#include <sys/time.h>
int main(int argc,char **argv) {
clock_t start, end;
double cpu_time_used;
struct timeval h,h2;
struct timezone tz;
int max=1000,acum=0,i,j;
gettimeofday(&h,&tz);
start = clock();
for (i=0;i<max;i++) {
acum+=1;
for (j=0;j<max;j++) {
acum=0;
}
}
end = clock();
gettimeofday(&h2,&tz);
cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
printf("%f %d %f %d %d %d",cpu_time_used,CLOCKS_PER_SEC,cpu_time_used,h.tv_usec,h2.tv_usec,h2.tv_usec-h.tv_usec);
}Para medir en milésimas de segundos, el campo tv.usec de la estructura timeval.

