I have this base class:

class LevelPlayer
{
protected:
   int level;
   int id;
public:
    LevelPlayer():id(-1){}
    LevelPlayer(int level,int id):level(level),id(id){}
    virtual ~LevelPlayer()=default;
    LevelPlayer(const LevelPlayer&)=default;
    LevelPlayer&  operator=(const LevelPlayer&)=default;
};

and this derived class:

class GroupPlayer: public LevelPlayer
{
private:
    IdPlayer* ptr;
public:
    GroupPlayer():LevelPlayer(),ptr(nullptr){}
    GroupPlayer(int level,int id,IdPlayer* ptr):LevelPlayer(level,id),ptr(new IdPlayer(*ptr)){}
    ~GroupPlayer()override=default;
    GroupPlayer(const GroupPlayer&);
    GroupPlayer&  operator=(const GroupPlayer&);
};

and for the copy ctor of the derived one I wrote this:

GroupPlayer::GroupPlayer(const GroupPlayer& player):ptr(new IdPlayer(*(player.ptr))){}

but I am not sure if it's correct ... should I also add LevelPlayer(player) ?

CodePudding user response：

Looking at the constructors and seeing

ptr(new IdPlayer(*ptr))
ptr(new IdPlayer(*(player.ptr)))

I come to the conclusion, you don't need the pointer the default and the copy constructor. Make the member and the second constructor

IdPlayer player;
GroupPlayer(int level, int id, const IdPlayer& player): LevelPlayer(level, id), player{player} {}

instead of IdPlayer* ptr; and remove other constructors. Finally, use spaces after punctuation marks in the code, this makes reading and code selection much easier.

CodePudding user response：

I am not sure if it's correct ... should I also add LevelPlayer(player) ?

Yes, the derived class copy constructor needs to call the base class copy constructor explicitly:

GroupPlayer::GroupPlayer(const GroupPlayer& player)
    : LevelPlayer(player), ptr(new IdPlayer(*(player.ptr)))
{
}

Since you have implemented the derived class copy constructor, and the base class constructor takes an input parameter, you need to pass in a value for that parameter. If you don't, the base class default constructor will be called instead, and thus level and id won't be copied from player.