How to create a class that can not be inherited by other classes?

Question

Can anyone tell how to create class so that it can not be inherited by any other classes.

class A {
  public :
          int a;
          int b;
};

class B : class A {
   public :
           int c;
};

in above program i do not want to allow other classes to be inherited by class B

It's not clear to me. You want to allow only `B` inherite from `A`? — songyuanyao, Aug 10 '16 at 10:31
Do you really mean "inherited *by*" or "inherited *from*" `class B`? — Galik, Aug 10 '16 at 10:39
Also, why do you want to do this? What problems would it cause? — Martin Bonner supports Monica, Aug 10 '16 at 11:14

score 13 · Answer 1 · edited Sep 24 '17 at 23:50

13

Mark the class final (since C++11):

class A final {
public :
    int a;
    int b;
};

edited Sep 24 '17 at 23:50

Jonathan Leffler

698,132
130
858
1,229

answered Aug 10 '16 at 10:28

Jarod42

190,553
13
166
271

score 5 · Answer 2 · answered Aug 10 '16 at 10:48

If you are using C++11 or later, you can use the final keyword, just as the other answer mentioned. And that should be the recommended solution.

However, if have to struggle with C++03 / C++98, you can make the class's constructors private, and create object of this class with a factory method or class.

class A {
private:
    A(int i, int j) : a(i), b(j) {}
    // other constructors.

    friend A* create_A(int i, int j);
    // maybe other factory methods.
};

A* create_A(int i, int j) {
    return new A(i, j);
}
// maybe other factory methods.

How to create a class that can not be inherited by other classes?

2 Answers2