Where should we free the dynamic memory if we do a "new" in one of our methods ?

[Ali89]

Hello,
If we request dynamic memory in the constructor of our class, we have to delete it in the destructor. But Where should we free the dynamic memory if we do a "new" in one of our methods ?

Cheers,
A.

[hamsterman]

You delete things when you don't need them any more. If, for example, you have a vector<int*> and your method pushes new int on it, delete the contents of that vector in the destructor. However if you have a single member int* and a method which assigns a new int to it, deleteing it only in the destructor would leak memory should you call that method more than once. In this case you should delete in the method:

struct S{
   int* i;
   S() : i(0) {}
   void method(){
      delete i;
      i = new int;
   }
   ~S(){ delete i; }
};

Note the constructor. deleteing an invalid pointer will end poorly, but deleteing a null pointer simply does nothing. (If you don't know what's with the :, google "initializer list". It's not necessary here though..)
Note the destructor. The method will only delete if called several times. You still need the destructor to delete the last instance.