Does multiple inheritance order matters?

I have come up with some confusing situations. Below are they.

#include <iostream>    using namespace std;    class Base {  public:      Base(int num) : data(num) {          cout << "BASE : " << num << endl;      }      virtual ~Base() = default;        virtual void func1() {          cout << "Base func1 called : " << data << endl;      }        virtual void func3() {          cout << "Base func3 called : " << data << endl;      }    private:      int data;  };    class Interface {  public:      Interface() {          cout << "INTERFACE : " << endl;      }      virtual ~Interface() = default;        virtual void func2() {          cout << "Interface func2 called" << endl;      }  };    class Derived : public Interface, public Base {  public:      Derived() : Base(0) {          cout << "DERIVED : hh" << endl;      }      virtual ~Derived() = default;        virtual void func1() override {          cout << "Derived fuc1 called" << endl;      }        virtual void func3() override {          cout << "Derived fuc3 called" << endl;      }        virtual void func2() override {          cout << "Derived fuc2 called" << endl;      }      };    int main() {      //Interface* a = new Derived(); // derived func2 called      //Base* a = new Derived();    // derived func1 called      //Derived* a = new Derived(); // derived func2 called      void* a = new Derived();      // derived func1 called      auto b = (Interface*)a;      b->func2();            ...  }  

When executing b->func2(), the result is different by the explicit type of variable a.

The results are in the comments.

Why are they different when executing b->func2()?

https://stackoverflow.com/questions/66809927/does-multiple-inheritance-order-matters March 26, 2021 at 09:44AM