I was writing code in C++ today and I had this bug I couldn''t figure out. The details are not important, but let''s just say I was very confused. Finally I isolated the error down to a destructor for a particular subclass not being called. And I made a valuable discovery. Take the program below: #include #include class Base { public: Base() { cout << "constructing base" << endl; } ~Base(){ cout << "destructing base" << endl; } }; class Sub : public Base { public: Sub(){ cout << "constructing sub" << endl; } ~Sub(){ cout << "destructing sub" << endl; } }; int main() { Base* TheClass; TheClass = new Base; delete TheClass; cout << "\n"; TheClass = new Sub; delete TheClass; system("PAUSE"); return 0; } Now, you would expect this to output this: constructing base destructing base constructing base constructing sub destructing sub destructing base But instead, (and I''ve tried this on two compilers) you get this: constructing base destructing base constructing base constructing sub destructing base The destructor for the subclass never gets called! I was shocked, but it does this on both Visual C++ and Dev-C++. Is there any way to get around this problem? Any other function you can declare to be virtual, but evidently not the destructor. Is it just me, or does this not seem terribly limiting? Is anyone else surprised by this as much as I am? I even tried making a virtual function called destroy() with different implementations in the base class and subclass, and calling it from the base class destructor, but this did not work either- it always calls the version of destroy() from the base class. Anybody know of another possible workaround?

Add ''virtual'' before the destructor for Base.

Martee
Magnum Games.NET
All your code are belong to us.

very simple...

your derived class has to have a virtual destructor, otherwise it wont be called.


virtual ~Derived() {}

Thanks guys! You''re lifesavers.