虚析构函数（派生类与基类）

1.情况1，

class Base {
 public:
~Base() {
  cout << "~Base()" << endl;
}
};

class Derived1 : public Base {
 public:
  Derived1():name_(new string("NULL")) {}
  Derived1(const string& n):name_(new string(n)) {}

  ~Derived1() {
    delete name_;
    cout << "~Derived1(): name_ has been deleted." << endl;
  }

 private:
  string* name_;
};

class Derived2 : public Base {
 public:
  Derived2():name_(new string("NULL")) {}
  Derived2(const string& n):name_(new string(n)) {}

  ~Derived2() {
    delete name_;
    cout << "~Derived2(): name_ has been deleted." << endl;
  }

 private:
  string* name_;
};

我们看下面对其析构情况进行测试：

int main() {
  Derived1* d1 = new Derived1();
  Derived2 d2 = Derived2("Bob");
  delete d1;
  return 0;
}

因为引用的类型就是派生类，所以析构函数，先删除派生类，后删除基类（建立一个派生类，一定会先建立一个基类（成员初始化列表语法）

结果：

~Derived1(): name_ has been deleted.

~Base()

~Derived2(): name_ has been deleted.

~Base()

情况二：

int main() {
  Base* base[2] = {
    new Derived1(),
    new Derived2("Bob")      
  };
  for (int i = 0; i != 2; ++i) {
    delete base[i];    
  }
  return 0;
}

没有虚析构函数，所以删除引用的类型

动态绑定：http://blog.csdn.net/iicy266/article/details/11906509

基类析构虚函数：因为动态绑定，先删除析构类，后删除基类

~Base()

~Base()

情况三：

class Base {
 public:
virtual ~Base() {
  cout << "~Base()" << endl;
}
};