c++ - Pass Parameter to Base Class Constructor while creating Derived class Object

Question

Consider two classes A and B

class A
{
public:
    A(int);
    ~A();
};

class B : public A
{
public:
    B(int);
    ~B();
};


int main()
{
    A* aobj;
    B* bobj = new bobj(5);    
}

Now the class B inherits A.

I want to create an object of B. I am aware that creating a derived class object, will also invoke the base class constructor , but that is the default constructor without any parameters.

What i want is that B to take a parameter (say 5), and pass it on to the constructor of A. Please show some code to demonstrate this concept.

Answer 1

Use base member initialisation:

class B : public A
{
public:
    B(int a) : A(a)
    {
    }
    ~B();
};