Un petite probeme dans prog C

#include <stdio.h>

typedef struct s_header {
  int value;
  int nbr;
  int idx;
} t_header;

void checking(int idx, int current, int *prev, int *nbr, t_header *header)
{
  if (current == *prev)
    *nbr += 1;
  else {
    if (*nbr >= header->nbr) {
      header->nbr = *nbr + 1;
      header->value = *prev;
      header->idx = idx - *nbr - 1;
    }
    *nbr = 0;
  }
  *prev = current;
}

int main()
{
  int tab[] = {12, 5, 5, -1, 2, 3, 3, 3, 3, 42, 5, 5, 5};
  int i, prev, nbr = 0, size = 13;
  t_header header;

  header.value = 0;
  header.nbr = 0;
  header.idx = 0;
  prev = tab[0];
  for (i = 1; i < size; i++)
    checking(i, tab[i], &prev, &nbr, &header);
  checking(i, prev + 1, &prev, &nbr, &header);
  printf("Longeur = %d\n", header.nbr);
  printf("Index de debut = %d\n", header.idx + 1);
  printf("Sequence = ");
  for (i = 0; i < header.nbr; i++)
    printf("%d ", header.value);
  printf("\n");
}