/*
 * right.c
 *
 * correct use of dynamic memory : malloc on the heap
 */

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

void printlist(int* intptr, int n){
  // print n numbers from a list.
  int i;
  printf("[");
  for (i=0; i<n; i++) printf("%i, ", intptr[i]);
  printf("]\n");
}

int* makelist(){
  int thelist[6] = {10, 20, 30, 40, 50, 60};
  int* result;
  result = malloc(sizeof(int)*6);         // allocate heap memory
  memcpy(result, thelist, sizeof(int)*6); // (destination, source, bytes)
  return result;
}

int triple(int i){
  return 3*i;
}

int main(){

  int* listy;
  int j=20;

  listy = makelist();  // dangling pointer ... 

  printlist(listy, 5);

  printf("j is %i, triple(j) is %i, triple(triple(j)) is %i \n",
         j, triple(j), triple(triple(j)));

  printlist(listy, 5);

  return 0;
}