STL Question not answered in FAQ

[Joe Buck]

> I am trying to use STL in the latest egcs release and have encountered a
> problem that seems fairly simple but I have yest to figure out why my code
> doesn't work.

It's because you defined a broken copy constructor in class C:

> class C {
>   friend class D;
>   vector<B> listb;
> public:
>   C() {}
>   C(int size) {
>     int i;
>     listb.reserve(size);
>     printf("Reserved %d for list B\n",size);
>     for (i = 0; i < size; i++) {
>       listb.push_back(B());
>     }
>   }
>   ~C() {}
>   C(const C& x) {}  // HERE.
>   C& operator= (const C& x) { }
> };

Then when you say

>       listc.push_back(C(sizeb));

The copy constructor is used to create the C objects in listc.
The resulting C object will have an empty vector.

DO NOT attempt to use the STL to store objects that do not meet the
requirements.  At minimum you need a copy constructor that does a
correct copy; for some algorithms you also need an assignment operator
that does a correct assignment (here your assignment operator is
also broken).