#include <stdio.h>
#define MAX 4

double boba (double d) {
  return d;
}  

struct s {
  double d1;
  struct s *next;
};

typedef double (*funcp) (double);

double foo (double a[], int size, funcp f) {
  int i;
  double soma = 0.0;
  for (i=0;i<size;i++) {
    soma += (*f)(a[i]);
  }
  return soma;
}

void boo (struct s *l, double n[], int size) {
  int i;
  for (i=0;i<size;i++){
    n[i] = l->d1;
    l = l->next;
  }
}

void bar (struct s *l, int size) {
  int i;
  for (i=0;i<size;i++) l[i].d1 = i;
}

float f(float x, int *pi) {
  *pi = (x<0)?0:1;
  return x;
}
  
double goo (double a[], int n) {
  double *pfloat;
  float res;
  int status;
  double sum = 0.0;
  for (pfloat = a; n-- ; pfloat++) {
    res = f((float)*pfloat, &status);
    if (status) sum += res;
  }
  return sum;
}

int main (void) {
  int i;
  double nums[MAX] = {0.0, 1.5, 2.5, -2.5};
  struct s lista[MAX];
 
  bar (lista, MAX);
  for (i=0;i<MAX-1;i++) {
    lista[i].next = &(lista[i+1]);
  }
  lista[MAX-1].next = NULL;

  printf ("%f\n", foo(nums, MAX, (funcp)boba));
  boo (lista, nums, MAX);
  printf ("%f\n", foo(nums, MAX, (funcp)boba));
  nums[3] = -3;
  printf ("%f\n", goo(nums, MAX));
  return 0;
}