c++ Multiple parents with same variable name

Question

class A{
    protected:
    int var;
};

class B{
    protected:
    int var;
};

class C : public A, public B {};

What happens here? Do the variable merges? Can I call one in specific like, B::var = 2, etc.

Did you even try the syntax you suggested (`B::var`)? It happens to be correct! — Ben Voigt, Sep 03 '12 at 23:37

user1071136 · Accepted Answer · 2012-09-03T23:58:09.980

16

You class C will have two variables, B::var and A::var. Outside of C you can access them like this (if you change to public:),

C c;
c.A::var = 2;

Attempting to access c.var will lead to an error, since there is no field with the name var, only A::var and B::var.

Inside C they behave like regular fields, again, with the names A::var and B::var.

edited Sep 03 '12 at 23:58

answered Sep 03 '12 at 23:40

user1071136

15,636
4
42
61

score 2 · Answer 2 · answered Sep 03 '12 at 23:39

2

You can access them in class C by A::var and B::var respectively.

Here is a link that covers the same problem.

answered Sep 03 '12 at 23:39

Seçkin Savaşçı

3,446
2
23
39

score 2 · Answer 3 · answered Sep 03 '12 at 23:40

If you only refer to var inside of C, the compiler does not know whether you mean A::var or B::var and the compiler will tell you that var is ambiguous. Therefore, you have to fully qualify the name when using var.

No merging happens, any instance of C will contain both variables.

c++ Multiple parents with same variable name

3 Answers3

Linked