Static variables in static method in base class and inheritance

Question

I have these C++ classes:

class Base
{
protected:
    static int method()
    {
        static int x = 0;
        return x++;
    }
};

class A : public Base         


        

Answer 1

I am pretty sure it will be shared between A and B.

If you want independent variables you can use the "Curiously Recurring Template Pattern" like:

template
class Base
{
protected:
    static int method()
    {
        static int x = 0;
        return x++;
    }
};

class A : public Base
{

};

class B : public Base
{

};

Of course if you want polymorphism, you would have to define a even "Baser" class which Base derives from, as Base is different from Base like:

class Baser
{
};

template
class Base : public Baser
{
protected:
    static int method()
    {
        static int x = 0;
        return x++;
    }
};

class A : public Base
{};

class B : public Base
{};

Now A and B can also be polymorphic.