Creating a public variable from another class (C++)

November 13, 2022

If you have two classes, class a and class b, could you create a variable in class a from class b?
main.cpp

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

class B {
    public:
        B() {
            test = A();
            test.<variable name> = <variable value>;
        }
};

The code above is just an example. It will probably cause an error.

"variable name" doesn’t exist in class A. Is there a way to create this variable for class A in the constructor for class B?

>Solution :

No, C++ is not Javascript. Types are strict and, after you define a type, there’s no way to modify it.

You can, however, create a local type in a function:

class B {
public:
    B() {
        struct A_extended : A {
            int i;
        };
        auto test = A_extended();
        test.i = 1;
    }
};