Inheriting constructors

Question

Why does this code:

class A
{
    public: 
        explicit A(int x) {}
};

class B: public A
{
};

int main(void)
{
    B *b = new B(5);
    delete b;
}
         


        

Answer 1

You have to explicitly define the constructor in B and explicitly call the constructor for the parent.

B(int x) : A(x) { }

or

B() : A(5) { }