objects-4.c

#include <stdio.h>

typedef struct
{
  int type;
} t_base;

typedef struct
{
  int type;
  int content;
} t_integer;

typedef struct
{
  int type;
  char *content;
} t_string;

int main (void)
{
  t_integer i = { 1, 42 };
  t_string s = { 2, "Hello, world!" };

  t_base *object[] = { (t_base *) &i, (t_base *) &s };

  for (int i = 0; i < 2; i++)
    if (object[i]->type == 1)
      printf ("Integer: %d\n", (t_integer *) object[i]->content);
    else if (object[i]->type == 2)
      printf ("String: \"%s\"\n", (t_string *) object[i]->content);

  return 0;
}