Question

I would like to simulate the object oriented programming, so in C++, let’s consider the following C code:

typedef struct tAnimal{
   char * name;
   int age;
}tAnimal;

typedef struct tAnimal2{
   char * name;
   int age;
   float size;
}tAnimal2;   

In C++ you can create a table of different objects which are inherited from the same class.
I would like to do the same in C, let’s consider the following code:

tAnimal ** tab;
tab = malloc(sizeof(tAnimal*)*2);
tab[0] = malloc(sizeof(tAnimal));
tab[1] = malloc(sizeof(tAnimal2));

Notice that the allocation works because malloc returns a void pointer, and C does not require casting. But I still have no access to the size field, because the type of tab elements is tAnimal after all.

Is there anyway to fix this?, I would like to stay away from void ** pointers.

Answer 1

If you want to access the size field you have to cast your pointer to tAnimal2. Note, the same would be true for C++.

You can kind of simulate inheritance by embedding the first struct at the beginning of the second:

struct tAnimal{
   char * name;
   int age;
};

struct tAnimal2{
  struct tAnimal parent;

  float size;
};