C++ questions, please ㅠㅜ

#include <iostream>
#include <vector>
#include <string>
class Npc 
{
public:
    std::string npc_arr;
};
class Guard :public Npc
{
public :
    std::string npc_arr;
    Guard(std::string npc_arr);
};
Guard::Guard(std::string npc_arr)
{
    this->npc_arr = npc_arr;
}
class Civil :public Npc
{

public:
    Civil(std::string npc_arr);
};
Civil::Civil(std::string npc_arr)
{
    this->npc_arr = npc_arr;
}
class InfoShower :public Npc
{
public:
    static void showInfo(std::vector<Npc*> npc_arr);
};

void InfoShower::showInfo(std::vector<Npc*> npc_arr)
{
    std::cout << "in the village";
    for (int i = 0; i < npc_arr.size(); ++i)
    {
        std::cout << npc_arr[i] << ",";
    }
    std::cout << "There is." << std::endl;
}

int main()
{
    std::vector<Npc*> npc_arr;
    npc_arr.push_back ("guard");
    npc_arr.push_back ("citizen");

    InfoShower::showInfo(npc_arr);
    return 0;
}