[cfe-dev] operator delete[] does not call derived class destructor

[Howard Hinnant]

On May 20, 2012, at 2:23 PM, bd satish wrote:

> Thanks Dmitri and Howard. Given this declaration:
> 
> Base* ptr = new Derived[3];
> 
> is there any other "fool-proof" alternative to ensure that the
> destructor of Derived objects are always called ? Since it works for
> scalar cases, like,
> 
> Base* ptr = new Derived;
> delete ptr;
> 
> as an end user, I expect the array version also to behave as such. I
> wonder why the standards decided to make this as "undefined" behavior.

I recommend turning on C++11 support (-std=c++11), turning on libc++ (-stdlib=libc++) and then using vector<unique_ptr<Base>>:

#include <iostream>
#include <memory>
#include <vector>

class Base
{
public:
 Base()    {    }

 virtual ~Base() {
   std::cout << "In destructor " <<  __func__  << std::endl;
 }
};

class Derived: public Base
{
public:
 Derived() {}

 ~Derived()  {
   std::cout << "In destructor for " <<  __func__ << std::endl;
 }
};

int main()
{
  typedef std::unique_ptr<Base> BasePtr;
  std::vector<BasePtr> ptr;
  ptr.push_back(BasePtr(new Derived));
  ptr.push_back(BasePtr(new Derived));
  ptr.push_back(BasePtr(new Derived));
}

In destructor for ~Derived
In destructor ~Base
In destructor for ~Derived
In destructor ~Base
In destructor for ~Derived
In destructor ~Base

Howard