Question

I have a few simple classes and I can’t get them to work.

TL;DR I have a “Player” instance, after I set some data to the instance, I can get it back. If I push the instance to std::vector Players; if I have Players.at(0).getName() it returns “”. The data is not there! Is gone. (Debugging the application I see “_name” set in “vPlayer” and in “Players” I see an element, with “_name” = “”)

Here is the code:

//Player.h
#ifndef PLAYER_H
#define PLAYER_H

#include <iostream>

class Player
{
public:
    Player();
    Player(const Player &Player);
    Player& operator=(const Player &Player);
    std::string getName();
    bool        setName(const std::string &name);
    bool        nameValid(const std::string &name);

private:
    std::string _name;
};



#endif



//Player.cpp

#include "Player.h"
#include <iostream>
#include <string>
using namespace std;

Player::Player()
{

}
Player::Player(const Player &Player)
{

}
Player& Player::operator=(const Player &Player) {
    return *this;
}

std::string Player::getName()
{
    return this->_name;
}

bool Player::setName(const std::string &name)
{
    if ( ! this->nameValid(name) )
    {
        return false;
    }

    this->_name = name;
    return true;
}

bool Player::nameValid(const std::string &name)
{
    return name.empty() == false;
}




//Map.h
#ifndef MAP_H
#define MAP_H

#define MAP_X 40
#define MAP_Y 40

#include "Player.h"
#include "Point.h"
#include <vector>

class Map
{
public:
    Map();
    bool movePlayer(Player &Player, Point &Point);
    std::vector<Player> getPlayers();
private:

};

#endif //MAP_H



//Map.cpp

#include "Map.h"
#include "Player.h"
#include "Point.h"
#include <iostream>
#include <string>

using namespace std;

Map::Map()
{

}

bool Map::movePlayer(Player &Player, Point &Point)
{
    return true;
}
std::vector<Player> Map::getPlayers()
{
    Player vPlayer;
    vPlayer.setName(std::string("test"));
    std::vector<Player> Players;

    Players.push_back(vPlayer);

    return Players;
}

in main:

  std::vector<Player> Players = vMap.getPlayers();
  cout<<"Test:"<<Players.at(0).getName()<<endl;

Answer 1

Your vector will contain copies of the elements you add to it. These copies will be added using Player::Player(const Player&) constructor.

This constructor (in your implementation) doesn’t set any value for the name.

Solutions:

• set the name in the copied object:

  Player::Player(const Player &Player)
: _name(Player._name)
{
}

(The same is true for your assignment operator)

• Remove the copy and assignment functionality and rely on the default. Because the name is a std::string, it will get a copy of the source player name by default.