fin du tp1

#include <stdio.h>

#include <stdlib.h>

struct cell_t {

  void* val;

  unsigned long int id;

typedef struct cell_t* list_t;

list_t list_empty(){

  return NULL;

}

int list_is_empty(list_t l){

int list_is_empty(list_t list){

  return list == NULL;

}

list_t list_push(list_t l, void* x){

  /*

  list_t celule = malloc(sizeof(struct cell_t));

  celule -> val = x;

  if (list_is_empty(l) != 1){

    celule -> id = l -> id + 1;

    celule -> next = l;

  }

  else{

    celule -> id = 1;

    celule -> next = NULL;

  }

  return celule;

  */

  list_t celule = malloc(sizeof(struct cell_t));

  celule -> val = x;

  celule -> next = l;

  if (list_is_empty(l)){

    celule -> id = 1;

  }

  else{

    celule -> id = l-> id + 1;

  }

  return celule;

}

list_t list_tail(list_t l){

  if(list_is_empty(l)){

    return NULL;

  }

  return l->next;

}

void* list_pop(list_t* l){ 

  void* res = (*l) -> val;

  list_t queue = (*l)->next;

  free(*l);

  *l = queue;

  return res;

}

void* list_top(list_t l){

  if(list_is_empty(l)){

    return NULL;

  }

  return l->val;

}

void list_destroy(list_t l, void (*free_void)(void*)){

  while(list_is_empty(l)){

    free_void(list_pop(&l));

  }

void list_destroy(list_t l, void (*free)(void*)){

}

// return the found element or NULL

void* list_in(list_t l, void* x, int (*eq)(void*, void*)){

  /*list_t tmp = l;

  while(tmp != NULL){

    if (eq(tmp->val,x)){

      return tmp->val;

    }

    tmp = tmp -> next;

  }

  return NULL;*/

  for(list_t curr = l; !list_is_empty(curr); curr = curr->next)

    if(eq(curr->val,x))

      return curr->val;

  return NULL;

}

unsigned long int list_len(list_t l){

  if(list_empty(l)){

    return 0;

  }

  return l->id;

}