デストラクタの呼ばれる順番

    cpp  / ノート

コンストラクタの逆、つまり

  • 派生クラスが先、基底クラスは後
  • 複数のクラスを継承する場合、継承宣言の最後から

の順番で呼ばれる。

#include <iostream>

class Base1 {
public:
  virtual ~Base1() {
    std::cout << "~Base1()\n";
  }
};

class Base2 {
public:
  virtual ~Base2() {
    std::cout << "~Base2()\n";
  }
};

class Base3 {
public:
  virtual ~Base3() {
    std::cout << "~Base3()\n";
  }
};

class Derived123: Base1, Base2, Base3 {
public:
  virtual ~Derived123() {
    std::cout << "~Derived123()\n";
  }
};

class Derived321: Base3, Base2, Base1 {
public:
  virtual ~Derived321() {
    std::cout << "~Derived321()\n";
  }
};

class Derived312: Base3, Base1, Base2 {
public:
  virtual ~Derived312() {
    std::cout << "~Derived312()\n";
  }
};

int main() {
  auto ptr123 = new Derived123();
  std::cout << "deleting Derived123* value\n";
  delete ptr123;
  std::cout << "\n";

  auto ptr321 = new Derived321();
  std::cout << "deleting Derived321* value\n";
  delete ptr321;
  std::cout << "\n";

  auto ptr312 = new Derived312();
  std::cout << "deleting Derived312* value\n";
  delete ptr312;

  return 0;
}

deleting Derived123* value
~Derived123()
~Base3()
~Base2()
~Base1()

deleting Derived321* value
~Derived321()
~Base1()
~Base2()
~Base3()

deleting Derived312* value
~Derived312()
~Base2()
~Base1()
~Base3()

参考