InitPointer 函数**ptr不太理解

来源：7-7 动态内存分配【突破面试高频考点】

Jonnyshao

2022-08-14

void InitPointer(int **ptr, int length, int default_value) {
  *ptr = malloc(sizeof(int) * length);
  for (int i = 0; i < length; ++i) {
    (*ptr)[i] = default_value;
  }
}

int main() {
  int * players;
  //InitPointer(&players, PLAYER_COUNT, 0);
  players = calloc(PLAYER_COUNT, sizeof(int));
  for (int i = 0; i < PLAYER_COUNT; ++i) {
    PRINT_INT(players[i]);
    players[i] = i;
  }
  PRINT_INT_ARRAY(players, PLAYER_COUNT);

  players = realloc(players, PLAYER_COUNT * 2 * sizeof(int));
  PRINT_INT_ARRAY(players, PLAYER_COUNT * 2);

  if (players) {

    free(players);
  } else {

  }


  return 0;
}

老师我有点笨，不太理这个**ptr 这个指针的指针最后指向哪里了？谢谢

写回答

1回答

bennyhuo

2022-08-14

int * players; InitPointer(&players, PLAYER_COUNT, 0);

注意看这两句，定义了一个 players 是一个指针，它本身也是一个变量，我们拿到它的地址，传给 InitPointer，这样在 InitPointer 里面，第一个参数也就是 **ptr 实际上指向的是 player 这个变量，我们通过 *ptr = ... 来修改 player 的值，这样实现对 player 的初始化。