What happens if an exception is raised in constructor [duplicate]

Question

Possible Duplicate:
What happens to base class destructor if a derived class destructor throws an exception

If I throw an exception in the constructor of a derived class, is the destructor called to clean up the base class?

Answer 1

The destructors of the base class(es) are then called in the reverse order.

Before that, the destructors of any already initialized member will also get called.

However, the destructor of the currently constructed derived-class won't get called, as this part of the object will not have been really constructed yet.

Answer 2

Yes. For example, consider:

#include <iostream>

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

class D : public B
{
public:
    D() { std::cout << "D()\n"; throw 23; }
    ~D() { std::cout << "~D()\n"; }
};

int main()
try
{
    D d;
    return 0;
}
catch(...) {}

Output:

B()
D()
~B()

Answer 3

http://www.parashift.com/c++-faq-lite/exceptions.html#faq-17.10

Every data member inside your object should clean up its own mess.

If a constructor throws an exception, the object's destructor is not run. If your object has already done something that needs to be undone (such as allocating some memory, opening a file, or locking a semaphore), this "stuff that needs to be undone" must be remembered by a data member inside the object.

Base destructors are guaranteed to be called, but not the destructor of the object itself.