Access to a public member of a base class from a derived class

Question

Is it possible to access the public member of the base class from an instance of the derived class in some other places in the program.

class base { public: int x; base(int xx){ x = xx; } }; class derived : base { public: derived(int xx) : base(xx){ } }; class main { public: derived * myDerived; void m1(){ myDerived = new derived(5); m2(myDerived); } void m2(derived * myDerived){ printf("%i", myDerived->x); } }; 

After the above code, I got the following error.

 `error: 'int base::x' is inaccessible` 

Answer 1

You inherit privately from the base class. Usually you need public inheritance:

 class derived : public base 

Here is the FAQ for private inheritance.

Answer 2

The problem is that you accidentally use private inheritance here

 class derived : base { 

This makes all members of the base class private in the derived class.

Change it to

 class derived : public base { 

and it will work as expected.

Answer 3

You must inherit from base public, then.

 class derived : public base { public: derived(int xx) : base(xx){ } }; 

Private inheritance is used in special circumstances, for example, when you have a has-a relationship between two classes, but you also need to override a member of the base class.

Answer 4

From outside the class, you can only access public members of the base base classes; and inheritance is private by default when defining a class using the class keyword.

To make it available, you need inheritance:

 class derived : public base ^^^^^^ 

Answer 5

Try:

 class derived : public base { ... }; 

Answer 6

Use public inheritance:

 class derived : public base { ... }; 

or

Make x private, not public, and use the following code:

 class Base { int x; public: Base (int xx) { x = xx; } void display() { cout << "x = " << x << endl; } }; class Derived : public Base { public: Derived (int xx) : Base (xx) { } }; int main() { Derived d1(2); Derived *d = new Derived(10); d->display(); d1.display(); return 0; }