Any ideas on determining cpu load in run-time?

Hello!
I have some interest in determining cpu load in run-time, but have no
idea how to implement this.

man getloadavg

Code:

---

FILE *file;
  unsigned proc_count = 0;
  long cpu = 0, nice = 0, system = 0, idle = 0, used = 0, total = 0;
  char buff[MAXBUFF];
  char *lpbuff = buff;
  size_t n = 0;
  char s_cpu_usage[MAXBUFF];
 
  bzero(s_cpu_usage, MAXBUFF);
  strcpy(s_cpu_usage, "");
 
  proc_count = get_nprocs();
 
  file = fopen("/proc/stat", "r");
  if(!file) 
  {
      sprintf(msg->error_str, "Error when getting CPU statistics. errno(%d) : %s", errno, strerror(errno));
      return 0;
  }
  //   
  getline(&lpbuff, &n, file);
  for (i = 0; i < proc_count; i++) 
  {
      fscanf(file, "%*s %ld %ld %ld %ld", &cpu, &nice, &system, &idle);
      used =  cpu+nice+system;
      total = cpu+nice+system+idle;
 
      bzero(buff, MAXBUFF);
      sprintf(lpbuff, "%ld %ld\n", used, total);
      strcat(s_cpu_usage, lpbuff);
  }
  fclose(file);

---

This is a part from one of my functions. I've corrected it slightly but I hope it will be clear for you.

Thanks all!
It seems with some #ifdef's and your samples I can forge cross-platform solution for problem.