What is difference between instantiating a C++ object using new vs. without new?

Samual Sam

Answered 1d 5h ago

In C++, we can instantiate the class object with or without using the new keyword. If the new keyword is not use, then it is like normal object. This will be stored at the stack section. This will be destroyed when the scope ends. But for the case when we want to allocate the space for the item dynamically, then we can create pointer of that class, and instantiate using new operator.

In C++, the new is used to dynamically allocate memory.

Example

#include <iostream>
using namespace std;
class Point {
   int x, y, z;
   public:
      Point(int x, int y, int z) {
         this->x = x;
         this->y = y;
         this->z = z;
      }
      void display() {
         cout << "(" << x << ", " << y << ", " << z << ")" << endl;
      }
};
int main() {
   Point p1(10, 15, 20);
   p1.display();
   Point *ptr;
   ptr = new Point(50, 60, 70);
   ptr->display();
}

Output

(10, 15, 20)
(50, 60, 70)