how to initialize post and friends parameters of new user
typedef struct user {
    char name[MAX_NAME];
    char profile_pic[MAX_NAME];  // This is a *filename*, not the file contents.
    struct post *first_post;
    struct user *friends[MAX_FRIENDS];
    struct user *next;
} User;

typedef struct post {
    char author[MAX_NAME];
    char *contents;
    time_t *date;
    struct post *next;
} Post;

void create_user(const char *name, User **user_ptr_add) {
}