Struct with array of structs of unknown size

Question

I\'ve been trying to wrap my head around this the whole day...

Basically, I have a struct called State that has a name and another one called StateMachine with a name, a

Answer 1

It looks like you're not allocating space for your states in the machine past the first one.

StateMachine * create_state_machine(const char* name) {
  StateMachine * temp;

  temp = malloc(sizeof(struct StateMachine));

  if (temp == NULL) {
    exit(127);
  }

  temp->name = name;
  temp->total_states = 0;

  temp->states = malloc(sizeof(struct State)); // This bit here only allocates space for 1.
  return temp;
}

You're probably better off putting an array of states of fixed size in the state machine struct. If that's not okay, you'll have to realloc and move the whole set around or allocate chunks and keep track of the current length, or make a linked list.

Incidentally, init, foo, and bar never get used.

Edit: What I'm suggesting looks like this:

#define MAX_STATES 128 // Pick something sensible.
typedef struct StateMachine {
  const char * name;
  int total_states;
  State *states[MAX_STATES];
} StateMachine;