final class in c++

Question

class Temp
{
private:
    ~Temp() {}
    friend class Final;
};

class Final : virtual public Temp
{
public:
     void fun()
     {
         cout<<\"In base\";         


        

Answer 1

I have modified the original code posted and verified this code in g++:

class Temp
{
private:
    Temp() {
        cout << "In Temp Class ctor" << endl;
    }
    ~Temp() {}
    friend class Final;
};

class Final : virtual public Temp
{
public:

    void fun()
     {
         cout<<"In base";
     }
};

class Derived : public Final
{
};

int main()
{
    Derived obj;
    obj.fun();

    return 0;
}

Result: $g++ one.cpp -o one -lm -pthread -lgmpxx -kgmp -lreadline 2>&1

one.cpp: In constructor 'Derived::Derived()': one.cpp:8:9: error: 'Temp::Temp()' is private Temp() {

one.cpp:25:11: error: within this context class Derived: public Final

one.cpp:11:9: error: 'Temp::~Temp()' is private ~Temp() {}

one.cpp:25:11: error: within this context class Derived : public Final

one.cpp:11:9: error: 'Temp::~Temp()' is private ~Temp() {}

Note: It's a best practice not use void with 'main'.

Thanks,