#include <stdio.h>

#define HEJ "Hello"
#define NL "\n"
#define MAX_ARRAY 10

struct mycomplex {
  int re;
  int im;
};

/*
  union u{
    int i;
    double r;
    char* s;
  };
*/

struct mys {
  int select;
  // union u;
};

int changeComplex(struct mycomplex *p)
{
  p->im = 100;
}

int changeInteger(int *p)
{
  *p = 200;
}

int dontChange(int i)
{
  i = 4000;
  printf("%d\n", i);
}

int main() {
  printf("Hello C World!\n");
  printf(HEJ);
  printf(NL);

  int i1 = 1;
  int i2 = 10;
  double d = 1.55;

  printf("%d\n", i1);
  i1 = 2;
  printf("%d\n", i1);
  printf("%g\n", d);

  struct mycomplex c, c2;
  c.re = 1;
  c.im = 2;
  printf(" imaginary part of complex is %d \n", c.im);
  c2 = c;
  c2.re = 5;
  printf(" %s real part of complex d is %d and img is: %d\n", "here", c2.re, c2.im);
  
  int myarray[] = {1, 2, 3, 4, 5, 6};

  for (int i=0; i<6; i++)
  {
    printf("%d ", myarray[i]);
  }
  printf("\n");
  myarray[3] = 10;
  for (int i=0; i<6; i++)
  {
    printf("%d ", myarray[i]);
  }
  printf("\n");

  int *p = &i1;
  printf("%p\n", p);
  printf("%p\n", myarray);
  int **pp = &p;
  printf("%d %d %d\n", i1, *p, **pp);
  i1 = 5;
  printf("%d %d\n", *p, **pp);
  i2 = i1;
  *p = 10;
  printf("%d %d %d\n", i1, *p, **pp);
  printf("%d\n", i2);

  i2 = *(myarray + 3);
  printf("%d = %d\n", i2, myarray[3]);
  myarray[3] = *(myarray + 5);
  printf("%d\n", myarray[3]);
  struct mycomplex c3 = c2;
  int i5 = c3.im;
  printf("%d\n", i5);
  changeComplex(&c3);
  printf("%d\n", c3.im);
  changeInteger(&i5);
  printf("%d\n", i5);
  dontChange(i5);
  printf("%d\n", i5);
  void *vp = (void*)(&i5);
  printf("%p\n", vp);
  printf("%g\n", ((struct mycomplex*)vp)->im);
  struct mycomplex *c4 = NULL;
  if (c4 != NULL)
    printf("%d\n", c4->im);

  int *arr = (int*)malloc(sizeof(int) * MAX_ARRAY);
  for (int i = 0; i < MAX_ARRAY; i++)
  {
     arr[i] = i;
     printf("%d ", arr[i]);
  }
  printf(NL);

  return 0;
}