Calculer le temps d’exécution du programme/temps écoulé en C

/*calculate program execute time */
#include
#include

int main(int argc, char *argv[]) {
   time_t start, stop;
   clock_t ticks; long count;

   time(&start);
   // Do stuff
   int i=0;

   while(i<50000)
   {
    printf("Work work %d\n", i);
        i++;
        ticks = clock();

   }

   time(&stop);

   printf("Used %0.2f seconds of CPU time. \n", (double)ticks/CLOCKS_PER_SEC);
   printf("Finished in about %.0f seconds. \n", difftime(stop, start));
   return 0;
}