C++ Copy and Move

copymove.cpp

#include <iostream>
#include <cstring>

struct Foo {
    Foo() {
      std::cout << "Constructor: " << this << std::endl;
      array = new char[4096];
    }

    ~Foo() {
      std::cout << "Destructor: " << this << std::endl;
      delete[] array;
    }

    Foo(const Foo& obj) {
      std::cout << "Copy Constructor: " << this << std::endl;
      array = new char[4096];
      std::memcpy(array, obj.array, 4096);
    }

    Foo(Foo&& obj) noexcept {
      std::cout << "Move Constructor: " << this << std::endl;
      array = obj.array;
      obj.array = nullptr;
    }

    Foo& operator=(const Foo& obj) {
      std::cout << "Copy Operator: " << this << " from " << &obj << std::endl;
      if (this == &obj) {
        return *this;
      }
      // delete[] array;
      // array = new char[4096];
      std::memcpy(array, obj.array, 4096);
      return *this;
    }

    Foo& operator=(Foo&& obj) noexcept {
      std::cout << "Move Operator: " << this << " from " << &obj << std::endl;
      if (this == &obj) {
        return *this;
      }
      delete[] array;
      array = obj.array;
      obj.array = nullptr;
      return *this;
    }

    char* array = nullptr;
};


#pragma clang diagnostic push
#pragma ide diagnostic ignored "performance-unnecessary-copy-initialization"
#pragma ide diagnostic ignored "UnusedValue"
#pragma ide diagnostic ignored "UnusedLocalVariable"

int main(int argc, char **argv) {
  std::cout << "## Foo a, b, c" << std::endl;
  Foo a, b, c;
  std::cout << std::endl << "## Foo v(a)" << std::endl;
  Foo v(a);
  std::cout << std::endl << "## Foo w = a" << std::endl;
  Foo w = a;
  std::cout << std::endl << "## Foo x" << std::endl;
  Foo x;
  std::cout << std::endl << "## x = a" << std::endl;
  x = a;
  std::cout << std::endl << "## Foo y = std::move(b)" << std::endl;
  Foo y = std::move(b);
  std::cout << std::endl << "## Foo z" << std::endl;
  Foo z;
  std::cout << std::endl << "## z = std::move(c)" << std::endl;
  z = std::move(c);
  std::cout << std::endl << "## z = Foo()" << std::endl;
  z = Foo();
  std::cout << std::endl << "## c = a" << std::endl;
  c = a;
  std::cout << std::endl << "## return 0" << std::endl;
  return 0;
}

#pragma clang diagnostic pop

result

## Foo a, b, c
Constructor: 004FFEB0
Constructor: 004FFEA4
Constructor: 004FFE98

## Foo v(a)
Copy Constructor: 004FFE8C

## Foo w = a
Copy Constructor: 004FFE80

## Foo x
Constructor: 004FFE74

## x = a
Copy Operator: 004FFE74 from 004FFEB0

## Foo y = std::move(b)
Move Constructor: 004FFE68

## Foo z
Constructor: 004FFE5C

## z = std::move(c)
Move Operator: 004FFE5C from 004FFE98

## z = Foo()
Constructor: 004FFE54
Move Operator: 004FFE5C from 004FFE54
Destructor: 004FFE54

## c = a
Copy Operator: 004FFE98 from 004FFEB0

## return 0
Destructor: 004FFE5C
Destructor: 004FFE68
Destructor: 004FFE74
Destructor: 004FFE80
Destructor: 004FFE8C
Destructor: 004FFE98
Destructor: 004FFEA4
Destructor: 004FFEB0