#include <stdio.h>
#include <time.h>

long int top_chrono;

void demarrer_chrono() {
        top_chrono = clock();
}

void stop_chrono() {
        long int arret_chrono = clock();
        fprintf(stderr, "Le calcul a pris %f secondes.\n",
                (float)(arret_chrono - top_chrono) / CLOCKS_PER_SEC);
}