C++ 对象数组指针

Question

I am new to C++ arrays and pointer and came across a few problems. I have some inquiries for the following code I wrote.

Version 1:

int main() 
{  
  string a, b;
  int age;
  Dog d[5];
  Dog *p = new Dog[5];

  for (int i = 0; i < 5; i++)
  {
    d[i].setwe(3 * i);
    d[i].setag(i);
    p[i] = Dog(d[i]);
  }

  p[5]->showCnt();
  //^^^^^^^^^^^^^^ Error above
  for (int j = 0; j < 5; j++)
  {
    delete [] p;
  }
  return 0;
}

Version 2:

int main() 
{  
  string a, b;
  int age;
  Dog d[5];
  Dog *p[5];

  for (int i = 0; i < 5; i++)
  {
    d[i].setwe(3 * i);
    d[i].setag(i);
    //p[i] = Dog(d[i]);
    p[i] = &d[i];
  }

  p[5]->showCnt();
  return 0;
}

From what I understand I might have written wrongly in version 1 but I want to understand why p is not seen as a pointer in version 1?

This is the hint I got from error: base operand of '->' has non pointer-type 'Dog' .

I am also unsure which is a better way(version 1 or version 2) to copy an object array to a pointer object array. I would like to apologise in advanced if I have understood it wrongly. Thank you.

Answer 1

p[5]->showCnt() is ilegal because your array of objects has only 5 positions, starting by 0 and ending on 4. So, you just have to replace p[5]->showCnt() by p[4]->showCnt() .

About the better version to use, use version 2 if you want to work with static sizes and use version 1 if you want to manage p dynamically to work with more than 5 objects at some moment of your program runtime. Short answer: version 1 is better!