gistfile1.c

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

struct node{
  void* data;
  struct node* next;
};

void set_int_value(struct node* node, int val)
{
  // ptr->data est de type void*
  int* i = malloc(sizeof (int));
  *i = val;
  node->data = i;
}

// Permet de créer une liste chainée {1,2,3}
struct node* create_list(int values[])
{
  size_t node_size = sizeof (struct node);
  struct node* current = malloc(node_size);
  struct node* head = current;
  for(int i = 0; i < 9; i++){
    current->next = malloc(node_size);
    set_int_value(current, values[i]);
    current = current->next;
  }
  current->next = NULL;
  set_int_value(current, values[9]);
  return head;
}

void* fold(struct node* head, void* acc, void*(*fun)(void*, void*)){
  struct node* current = head;
  while(current){
    acc = fun(acc, current->data);
    current = current->next;
  }
  return acc;	
}

void* add(void* a, void* b)
{
  int* i = malloc(sizeof (int));
  *i = *((int*)a) + *((int*)b);
  return i;
}

void* multiply(void* a, void* b)
{
  int* i = malloc(sizeof (int));
  *i = *((int*)a) * *((int*)b);
  return i;
}

void* sum(struct node* head)
{
	int* seed = malloc(sizeof (int));
	*seed = 0;
	return fold(head, seed, add);
}

void map(struct node* head, void(*fun)(void*))
{
  struct node* current = head;
  while(current){
    fun(current->data);
    current = current->next;
  }	
}	

void print_int(void* val)
{
  printf("%d", *((int*)val));
}

void print_int_for_list(void* val)
{	
  printf("%d -> ", *((int*)val));
}

void print(struct node* head)
{
  map(head, print_int_for_list); 
  printf("NULL\n");
}

void* count(struct node* head)
{
  int* accumulator = malloc(sizeof (int));
  struct node* current = head;
  while(current){
    current = current->next;
    (*accumulator)++;
  }
  return accumulator;
}

void* value_at(struct node* head, int index)
{
  struct node* current = head;
  int* length = malloc(sizeof (int));
  length = ((int*)count(head));
  if(index < *length){
    for(int x = 0; x < (index - 1); x++){
      current = current->next;
    }
  }
  return current->data; 
} 

int main(void)
{	
  int values[10] = {1,2,3,4,5,6,7,8,9,10};
  struct node* l = create_list(values);
  print(l);
  print_int(sum(l));
  printf("\n");
  print_int(value_at(l, 6));
  printf("\n");
}

Un truc que je ne comprends pas trop : je comptais passer un tableau à la fonction qui crée la liste chainée pour les valeurs des cellules, mais apparemment déterminer la taille du tableau n'est pas aussi aisé que je l'aurais cru.

Connais-tu une bonne façon de gérer ce cas ? Si tu piges pas ce que je raconte on en reparle sur IRC.