Shallow Vs Deep Copy.cpp

// 📂 Shallow vs deep copy

// 📂 SHALLOW COPY CONSTRUCTOR EXAMPL
#include <iostream>
using namespace std;

class abc {
public:
  int x;
  int *y;

  abc(int _x, int _y) : x(_x), y(new int(_y)) {}

  // Default dumb copy constructor: it is shallow copy
  abc(const abc &obj) {
    x = obj.x;
    y = obj.y;
  }

  void print() const {
    printf("PTR X:%p\nX:%d\nPTR Y:%p\nContent of Y:%d\n\n", &x, x, y, *y);
  }
};

int main() {
  abc a(1, 2);
  cout << "Printing a\n";
  a.print();

  abc b = a;
  cout << "Printing b\n";
  b.print();

  // update the value of Y of b
  *b.y = 20;

  cout << "Printing a\n";
  a.print();

  cout << "Printing b\n";
  b.print();
  return 0;
}

/*
Printing a
PTR X:0x7ffeadd4bd40
X:1
PTR Y:0x9d2eb0
Content of Y:2

Printing b
PTR X:0x7ffeadd4bd30
X:1
PTR Y:0x9d2eb0
Content of Y:2

Printing a
PTR X:0x7ffeadd4bd40
X:1
PTR Y:0x9d2eb0
Content of Y:20

Printing b
PTR X:0x7ffeadd4bd30
X:1
PTR Y:0x9d2eb0
Content of Y:20
*/

// 📂 DEEP COPY CONSTRUCTOR EXAMPLE
#include <iostream>
using namespace std;

class abc {
public:
  int x;
  int *y;

  abc(int _x, int _y) : x(_x), y(new int(_y)) {}

  // Our Smart copy constructor: it is Deep Copy
  abc(const abc &obj) {
    x = obj.x;
    y = new int(*obj.y);
  }

  void print() const {
    printf("PTR X:%p\nX:%d\nPTR Y:%p\nContent of Y:%d\n\n", &x, x, y, *y);
  }
};

int main() {
  abc a(1, 2);
  cout << "Printing a\n";
  a.print();

  abc b = a;
  cout << "Printing b\n";
  b.print();

  // update the value of Y of b
  *b.y = 20;

  cout << "Printing a\n";
  a.print();

  cout << "Printing b\n";
  b.print();
  return 0;
}

/*
Printing a
PTR X:0x7ffe2c9bc220
X:1
PTR Y:0x140beb0
Content of Y:2

Printing b
PTR X:0x7ffe2c9bc210
X:1
PTR Y:0x140c2e0
Content of Y:2

Printing a
PTR X:0x7ffe2c9bc220
X:1
PTR Y:0x140beb0
Content of Y:2

Printing b
PTR X:0x7ffe2c9bc210
X:1
PTR Y:0x140c2e0Content of Y:20
*/

// 📂 SHALLOW COPY CONSTRUCTOR DISADVANTAGE
#include <iostream>
using namespace std;

class abc {
public:
  int x;
  int *y;

  abc(int _x, int _y) : x(_x), y(new int(_y)) {}

  // Default dumb copy constructor: it is Shallow Copy
  abc(const abc &obj) {
    x = obj.x;
    y = obj.y;
  }

  void print() const {
    printf("PTR X:%p\nX:%d\nPTR Y:%p\nContent of Y:%d\n\n", &x, x, y, *y);
  }

  ~abc() {
    cout << "DTOR Called\n";
    delete y;
  }
};

int main() {
  // abc a(1,2);
  // cout<< "Printing a\n";
  // a.print();

  // abc b = a;
  // cout<< "Printing b\n";
  // b.print();

  abc *a = new abc(1, 2);
  abc b = *a;
  delete a;
  b.print();
  return 0;
}

/*
DTOR Called

PTR X:0x7ffdacc998d0
X:1
PTR Y:0x11e9ed0
Content of Y:0

DTOR Called

free(): double free detected in tcache 2
Aborted
*/