Question

#include <iostream>

using namespace std;
int *p1;
struct base
{
    base():a(10){}
    int a;
    ~base()
    {
        cout << "~base()\n";
    }
};

struct derive:public base
{
    derive():b(5){

        p1=&b;
        cout << p1 << "\n";

    }
    int b;
    ~derive()
    {
        cout << "~derive()\n";
    }
};
int main()
{
    base *p = new derive;
    delete(p);
    cout << *p1;
    return 0;
}

I think b of derive shoule not be deleted,but what p1 pointed was deleted.
how it works when I delete pointer of a base class that was pointed to an derive class when no dynamic inherit occured?
sorry for my english.

Answer 1

It’s undefined behavior, because the base class destructor is not virtual. UB means anything can happen.

Don’t delete a derived object through a base class if the base class doesn’t have a virtual destructor.