aufgabe-2b.c

#include <stdio.h>

#define ANIMAL     0
#define WITH_WINGS 1
#define WITH_LEGS  2

typedef struct animal
{
  int type;
  char *name;
} animal;

typedef struct with_wings
{
  int wings;
} with_wings;

typedef struct with_legs
{
  int legs;
} with_legs;

int main (void)
{
  animal *a[2];

  animal duck;
  a[0] = &duck;
  a[0]->type = WITH_WINGS;
  a[0]->name = "duck";
  ((with_wings *) a[0])->wings = 2;

  animal cow;
  a[1] = &cow;
  a[1]->type = WITH_LEGS;
  a[1]->name = "cow";
  ((with_legs *) a[1])->legs = 4;

  for (int i = 0; i < 2; i++)
    if (a[i]->type == WITH_LEGS)
      printf ("A %s has %d legs.\n", a[i]->name,
              ((with_legs *) a[i])-> legs);
    else if (a[i]->type == WITH_WINGS)
      printf ("A %s has %d wings.\n", a[i]->name,
              ((with_wings *) a[i])-> wings);
    else
      printf ("Error in animal: %s\n", a[i]->name);

  return 0;
}