5.2 Dynamic Memory Allocate Object in C++

5.2.1 make object in heap segmen

How object allocate dynamic memory

it need “object pointer variable” to allocate memory in heap segment. class type momory create through new operator and then new pass address value

mousePoint *pt;
pt = new MousePointer(10, 20)

1. declare object pointer
   mousePoint *pt;
2. allocate object throgh new operator and pointer variable assigned object address
   pt = new MousePoint(10, 20)

#include <iostream>
using namespace std;

class MousePoint {
 public:
  MousePoint();
  MousePoint(int nX, int xY);
  void SetXY(int X, int Y);
  int GetX() const;
  int GetY() const;

 private:
  int x, y;
};

MousePoint::MousePoint() {}
MousePoint::MousePoint(int nX, int nY) {
  x = nX;
  y = nY;
}
void MousePoint::SetXY(int nX, int nY) {
  x = nX;
  y = nY;
}

int MousePoint::GetX() const { return x; }
int MousePoint::GetY() const { return y; }

int main() {
  MousePoint *pt;
  pt = new MousePoint(10, 20);
  cout << "X coordinate: " << pt->GetX() << ", "
       << "Y coordinate: " << pt->GetY() << endl;

  delete pt;

  return 0;
}

5.2.2 array of object pointers

Can allocate lot a object point as Array and it can create object on dynamic memory. it’s called “Array of Object Pointers”.

// on the stack
MousePointer *pArr[3];

// on the heap
pArr[0] = new MousePointer(10, 20);
pArr[1] = new MousePointer(100, 200);
pArr[2] = new MousePointer(1000, 2000);

#include <iostream>
using namespace std;

class MousePoint {
 public:
  MousePoint();
  MousePoint(int nX, int xY);
  void SetXY(int X, int Y);
  int GetX() const;
  int GetY() const;

 private:
  int x, y;
};

MousePoint::MousePoint() {}
MousePoint::MousePoint(int nX, int nY) {
  x = nX;
  y = nY;
}
void MousePoint::SetXY(int nX, int nY) {
  x = nX;
  y = nY;
}

int MousePoint::GetX() const { return x; }
int MousePoint::GetY() const { return y; }

int main() {
  MousePoint *pArr[3];
  pArr[0] = new MousePoint(10, 20);
  pArr[1] = new MousePoint(100, 200);
  pArr[2] = new MousePoint(1000, 2000);

  for(int i =0; i < 3; i++) {
    cout << pArr[i]->GetX() << ", " << pArr[i]->GetY() << endl;
  }

  for(int i =0; i < 3; i++) {
    delete pArr[i];
  }
}

• 📚 reference
  • book - C++ 프로그래밍과 STL (이창현)
  • Photo by Fahrul Azmi on Unsplash