how to generate two random arrays in c

Question

I want to generate two random arrays no matter what i tried but the two tables are always identical

double *init_rand_w(double tableau[],int tailleTableau) {
    //double *tableau=malloc(tailleTableau*sizeof(double));
    srand(time(NULL));

    for (int i = 0 ; i < tailleTableau ; i++)
    {

        tableau[i]=((double)rand())/((double)RAND_MAX);
    }

    return  tableau;
}

int main()
{
    double *t1=(double*)malloc(sizeof(double)*10);
    double *t2=(double*)malloc(sizeof(double)*10);

    t1=init_rand_w(t1,5);
    t2=init_rand_w(t2,5);

    shuffle(t2,5);

    printf("***************************\n");

    for (int x = 0; x <5; x++)
    {
        printf("%f  ,  %f \n", t1[x],t2[x]);
    }
}

Don't call `srand` twice. Your loops certainly run fast enough that your two calls to `srand` happen in the same second, so `time()` returns the same value. — Steve Summit, Dec 15 '21 at 22:23
Call `srand(time(NULL));` once at the beginning of your program. — Retired Ninja, Dec 15 '21 at 22:24

score 1 · Answer 1 · answered Dec 15 '21 at 22:25

You should just call srand once at the beginning of your program. It initializes the state of the random number generator. You are currently calling it twice, and you are likely giving it the same seed value each time you call it (since your program would take a lot less than one second to run), so you would get the same sequence of random numbers.

how to generate two random arrays in c

1 Answers1