int a = 5; // get memory address of a cout << &a << endl; // 0x7ffee707c75c // pointer variable to store address of a int* ptr = &a; // reference: output is address cout << ptr << endl; // 0x7ffee707c75c // dereference: output is value at pointer cout << *ptr << endl; // 5 // null pointer int* np = NULL; cout << np << endl; // 0x0