Question

This is the code:

#include <string>
#include <vector>
#include <iostream>
using namespace std;
class A {
public:
  virtual const string f() const { return "A"; }
};
class B : public A {
public:
  const string f() const { return "B"; }
};
int main(int ac, char** av) {
  vector<A> v;
  v.push_back(B());
  cout << v.at(0).f() << endl;
  return 0;
}

Expected result is B, but it’s A. As I understand object slicing is taking place. How to avoid it? Shall I store pointers in vector instead of object instances? Is this the only choice?

Answer 1

You need to store pointers. If these refer to dynamically allocated objects, use smart pointers.