CODEWITHSUNDEEP
cpointersstructmalloc
minnymauer
minnymauer

Reputation: 374

Initializing structs inside a struct with malloc?

Here is my data structure for an NPC.

typedef struct npc {
   npc_characteristics_t characteristics;
   position pc_last_known_position;
   position npc_position;
   int speed;
   int turn;
} npc_t;

I initialize it with this: 

void gen_monsters(dungeon *d, int nummon) {
  int i;
  for (i = 0; i < nummon; i++) {
    npc_t *monster;
    if (!(monster = malloc(sizeof (*monster)))) {
      perror("malloc");
      exit(1);
    } else {
      init_monster(monster);
    }
  }
}

static void init_monster(npc_t *m) {
  int charact = rand()%3;

  if (charact == 0) 
    m->characteristics = 0x00000000;
  else if (charact == 1)
    m->characteristics = NPC_SMART;
  else if (charact == 2)
    m->characteristics = NPC_TELEPATH;

  m->pc_last_known_position = {0, 0};
  m->npc_position = {0, 0};
  m->speed = rand() % 15 + 6;
  m->turn = 0;
}

And this is my position struct:

typedef struct position_t {
  int x, y;
} position;

Why isn't this working? I'm getting this:

npc.c:22:1: error: expected identifier or ‘(’ before ‘}’ token
 }
 ^
npc.c: In function ‘init_monster’:
npc.c:35:30: error: expected expression before ‘{’ token
  m->pc_last_known_position = {0,0};
                          ^
npc.c:37:20: error: expected expression before ‘{’ token
  m->npc_position = {0,0};
                    ^
make: *** [npc.o] Error 1

And what's the correct way to do this? I'm supposed to use malloc to get some room in memory for the structure right? But then wouldn't I need to do this for position also and give the NPC the pointer to the position struct?

Upvotes: 2

Views: 480

Answers (1)

Iharob Al Asimi
Iharob Al Asimi

Reputation: 53006

Although you can't use an initializer list that way, you can use the memset() function from the string.h header, this way

memset(&(m->pc_last_known_position), 0, sizeof(m->pc_last_known_position));
memset(&(m->npc_position), 0, sizeof(m->pc_last_known_position));

Upvotes: 2

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