sample.cpp

#include <vector>
#include <string>
#include <sstream>
#include <iostream>
#include <memory>
#include <string.h>
#include <cstdarg>
#include <type_traits>

using namespace std;



class VoiceActress{
public:    
    virtual void greeting() = 0;
    virtual ~VoiceActress()=default;
};

class Naobou  : public VoiceActress{
public:    
    void greeting(){
        cout << "I'm nao!" << endl;
    }
};
class Kayanon : public VoiceActress{
public:    
    void greeting(){
        cout << "I'm kayanon!" << endl;
    }
};
class Nanasan : public VoiceActress{
public:    
    void greeting(){
        cout << "I'm nanasama!" << endl;
    }
};

void greeting(VoiceActress* vc){
    vc->greeting();
}

int main(){
    vector<VoiceActress*> actresses;
    actresses.push_back(new Naobou());
    actresses.push_back(new Nanasan());
    actresses.push_back(new Kayanon());
    
    for(auto&& a: actresses){
        greeting(a);
    }
    return 0;   
}