change to asprintf()
char *list_users(const User *curr) {
    printf("User List\n");
    
    // keep track of number of users --> size of array of strings
    int num_users = 0;
    while (curr!= NULL) {
        num_users++;
        curr = curr->next;
    }

    // allocate space for arr
    char **arr = malloc(sizeof(char *) * num_users);

    // for loop to insert a user per index in the array
    char *new_user;
    for (int i = 0; i < num_users; i++) {
        while (curr != NULL) {
            new_user = snprintf("\t%s\n", strlen(curr->name), curr->name);
            arr[i] = new_user;
            curr = curr->next;
        }
    }
    // return the array of strings
    return *char;
}printf("------------------------------------------\n");