Hashing table essentials C

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

#define TAILLE 20 //taile de la table de hachage

struct Element {
   int donnees;
   int id;
};

struct Element* tableHachage[TAILLE];
struct Element* elVide;
struct Element* el;

int hachage(int id) {
   return id % TAILLE;
}

struct Element *chercher(int id) {

   int posHachage = hachage(id);

   while(tableHachage[posHachage] != NULL) {

      if(tableHachage[posHachage]->id == id)
         return tableHachage[posHachage];

      ++posHachage;

      posHachage %= TAILLE;
   }

   return NULL;
}

void inserer(int id,int donnees) {

   struct Element *el = (struct Element*) malloc(sizeof(struct Element));
   el->donnees = donnees;
   el->id = id;

   int posHachage = hachage(id);

   while(tableHachage[posHachage] != NULL && tableHachage[posHachage]->id != -1) {

      ++posHachage;

      posHachage %= TAILLE;
   }

   tableHachage[posHachage] = el;
}

struct Element* supprimer(struct Element* el) {
   int id = el->id;

   int posHachage = hachage(id);

   while(tableHachage[posHachage] != NULL) {

      if(tableHachage[posHachage]->id == id) {
         struct Element* temp = tableHachage[posHachage];

         tableHachage[posHachage] = elVide;
         return temp;
      }

      ++posHachage;

      posHachage %= TAILLE;
   }

   return NULL;
}

void afficher() {
   int i = 0;

   for(i = 0; i<TAILLE; i++) {

      if(tableHachage[i] != NULL)
         printf(" (%d,%d)",tableHachage[i]->id,tableHachage[i]->donnees);
      else
         printf(" ~~ ");
   }

   printf("\n");
}

int main() {
   elVide = (struct Element*) malloc(sizeof(struct Element));
   elVide->donnees = -1;
   elVide->id = -1;

   inserer(1, 20);
   inserer(2, 70);
   inserer(42, 80);
   inserer(4, 25);
   inserer(12, 44);
   inserer(14, 32);
   inserer(17, 11);
   inserer(13, 78);
   inserer(37, 97);

   afficher();
   el = chercher(37);

   if(el != NULL) {
      printf("Element trouve : %d\n", el->donnees);
   } else {
      printf("Element pas trouve\n");
   }

   supprimer(el);
   el = chercher(37);

   if(el != NULL) {
      printf("Element trouve : %d\n", el->donnees);
   } else {
      printf("Element pas trouve \n");
   }
}