Time spent doing something

time_spent.c

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

long timevaldiff(struct timeval *starttime, struct timeval *finishtime) {
  long msec;
  msec=(finishtime->tv_sec-starttime->tv_sec)*1000;
  msec+=(finishtime->tv_usec-starttime->tv_usec)/1000;
  return msec;
}

int main () {

  struct timeval start, finish;
  long msec;


  while(1){
    gettimeofday(&start, NULL);
    // do Something 
    gettimeofday(&finish, NULL);
    msec = timevaldiff(&start, &finish);
    printf("Elapsed time for: %d milliseconds.\n", msec);
    sleep(1);    
  }
  
  exit(0);
}