Linked List - Aoclel

#include <stdio.h>
#include <stdlib.h>

typedef struct _mark {
  unsigned int mark;
  struct _mark* next;
} Mark;

Mark* append(Mark* head, unsigned int mark);
void print_list(Mark* head);
void free_list(Mark* head);

int main() {
  printf("Linked List\n");

  // Inizializziamo una lista vuota
  // struct _mark *marks_list = NULL;
  Mark* marks_list = NULL;

  marks_list = append(marks_list, 11);
  marks_list = append(marks_list, 12);
  marks_list = append(marks_list, 32);
  marks_list = append(marks_list, 2);
  marks_list = append(marks_list, 1);
  marks_list = append(marks_list, 24);
  marks_list = append(marks_list, 21);
  marks_list = append(marks_list, 31);

  print_list(marks_list);

  free_list(marks_list);
  return 0;
}

void print_list(Mark* head) {
  // Dalla testa alla coda, stampo tutti i mark e ogni volta passo al next
  // finchè non diventa NULL
  for (Mark* _iterator = head; _iterator != NULL; _iterator = _iterator->next) {
    printf("%u -> ", _iterator->mark);
  }

  printf("NULL\n");
}

void free_list(Mark* head) {
  if (head == NULL) return;

  printf("HEAD: %d\n", head->mark);

  if (head->next == NULL) {
    printf("Killing: %d\n", head->mark);
    free(head);
    return;
  }

  free_list(head->next);
  printf("Killing: %d\n", head->mark);
  free(head);
}

Mark* append(Mark* head, unsigned int mark) {
  // Se la lista è inizialmente vuota
  if (head == NULL) {
    Mark* new_head = (Mark*)malloc(sizeof(Mark));
    new_head->mark = mark;
    new_head->next = NULL;

    return new_head;
  }

  // Scorre finchè c'è un next
  Mark* _iterator;
  for (_iterator = head; _iterator->next != NULL;) {
    _iterator = _iterator->next;
  }

  // Quando il next è NULL lo alloco
  _iterator->next = (Mark*)malloc(sizeof(Mark));
  _iterator->next->mark = mark;
  _iterator->next->next = NULL;

  return head;
}

// *a = 0x134;
// *a = fun() = 0x134

// MEMORIA[0x134]  = { mark: 29, next: 0x700 };
// MEMORIA[0x700]  = { mark: 22, next: 0x800 };
// MEMORIA[0x800] = { mark: 11, next null };

// fun(a, b, c) {
//   *it = a;
//   finche( NULL != null) {
//     it = it -> NULL;
//   }
//   it -> next = { mark: 11, next null;}
//   return 0x134;
// }