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(); }; 

Answer 2

B::B(int x):A(x) {     //Body of B constructor }