virtual base class and initialization lists [duplicate]

Answer 1

Since the Base does not have an implicit constructor and both C1 and C2 are virtual bases, you would have to change it like this (and also add semicolons after the rest of the class declarations as pointed out by Charles Bailey)

class Join : public D1, public D2 {
public:
    Join() : Base(3) {};
    ~Join(){};
};

int main()
{
   Join j;
   cout << j.x << endl;
}

Then it would print 3 to the standard output