How can I generate a 16 digit random number with rand() function in C?

I'm trying to generate a 16 digit random card number in a function for a bank account creating sample. I tried the code below, but it didn't work.

void generate_card_number() {
    srand(time(0));
    long long int cardnumber = 0;
    int i, randctrl;

    for (i = 0; i < 15; i++) {
        do {
            randctrl = rand() % 9;
        } while (randctrl == 0);
        cardnumber += ((10^i) * randd);
    }
    printf("\nThe Card Number : %lld", cardnumber);
}

Could you help me, please?