Basic inheritance using structs in C

inheritance.c

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

// super "class"
typedef struct
{
  int age;
  double weight;
} Animal;

// sub "class"
typedef struct
{
  Animal super;
  double wingspan;
} Bird;

// an init method (a constructor) can set up the objects
void new_Animal (Animal *self, int age, double weight)
{
  self->age = age;
  self->weight = weight;
}

// a subclass init
void new_Bird (Bird *self, int age, double weight, double wingspan)
{
  // in order to access the super class we typecast the bird pointer to Animal
  // and call the animal init function
  new_Animal( (Animal *) self, age, weight );

  // set additional fields relevant to our subclass
  self->wingspan = wingspan;
}

// different functions that access the objects need to chain the calls to the
// superclass equivalent functions first, before doing subclass specifics
void print_animal(const Animal *self)
{
  printf("animal: %d age, weights %.2fkg\n", self->age, self->weight);
}

void print_bird(const Bird *self)
{
  // again cast to treat it like Animal class
  print_animal( (Animal *) self );
  printf("wingspan: %.2f\n", self->wingspan);
}

int main(int argc, char const *argv[])
{
  // since the Bird's first element is a superclass Animal and the have
  // the same memory address, we can cast the Bird to an animal

  // the addresses are the same, of course lol
  Bird b;
  printf("%p\n", &b);
  printf("%p\n", &b.super);

  // running subclass specific function will chain call the superclass
  // init and print functions
  new_Bird(&b, 10, 43, 2);
  print_bird(&b);

  return EXIT_SUCCESS;
}