在向量中存储基类指针的c多态性

Question

我有一个基类，然后有两个派生类。我使用基类的指针在Vector中存储派生类对象。现在我必须打印存储在vector中的数据

如何从向量中检索对象。

如何确定检索到的对象属于哪个派生类。

    class CricketPlayer:public SlumsMember
{
    protected:
        int runsScored;
        int wicketsTaken;
        int catchesTaken;
    public:
        CricketPlayer(int rNo,string n,double theGpa,char typ,int rScore,int theWicketTaken,int theCatchTaken);
        int getRunsScored();
        int getWicketsTaken();
        int getCatchesTaken();

};

    CricketPlayer::CricketPlayer(int rNo,string n,double theGpa,char typ,int rScore,int theWicketTaken,int theCatchTaken):
                   SlumsMember(rNo,n,theGpa,typ)
                   {
                      runsScored=rScore;
                      wicketsTaken=theWicketTaken;
                      catchesTaken=theCatchTaken;
                   }



    int CricketPlayer::getRunsScored()
    {
        return (runsScored);

    }
    int CricketPlayer::getWicketsTaken()
    {
        return (wicketsTaken);
    }
    int CricketPlayer::getCatchesTaken()
    {
        return(catchesTaken);
    }

class FootballPlayer:public SlumsMember
{
 protected: 
    int goalsScored;
    int assists;
    int interceptions;
 public:

    FootballPlayer(int rNo,string n,double theGpa,char typ,int theGoalsScored,int theAssists,int theInterceptions);
    int getGoalsScored();
    int getAssists();
    int getInterceptions();

};

   FootballPlayer::FootballPlayer(int rNo,string n,double theGpa,char typ,int theGoalsScored,int theAssists,int theInterceptions):
                    SlumsMember(rNo,n,theGpa,typ)
                    {
                            goalsScored=theGoalsScored;
                            assists=theAssists;
                            interceptions=theInterceptions;
                    }

    int FootballPlayer::getGoalsScored()
    {
            return(goalsScored);

    }
    int FootballPlayer::getAssists()
    {
        return(assists);

    }
    int FootballPlayer::getInterceptions()
    {
            return(interceptions);
    }

在这里，我使用向量将对象存储在向量中。

int main() {

vector<SlumsMember> members;

SlumsMember *slumsMember;

                    slumsMember=new FootballPlayer(rNo,name,gpa,ch,a,b,c);


                    slumsMember=new CricketPlayer(rNo,name,gpa,ch,a,b,c);





            members.push_back(*slumsMember);

SlumsMember *mbr;
 for(int i=0;i<members.size();i++)
 {
    mbr=members[i];

  //How to make sure to which base class an object retrieved belongs to and how to access it.

 }     







return 0;
}

Answer 1

我清理了你的代码。。。

class SlumsMember
{

试试这个...使getWicketsTaken函数在基类中为虚拟的

public:
   virtual int getWicketsTaken();

   int rollNumber;
   string name;
   double gpa;
   char type;
};



class CricketPlayer:public SlumsMember
{
public:

重写有助于防止类型重载

   int getWicketsTaken() override;

   int runsScored;
   int wicketsTaken;
   int catchesTaken;
};



class FootballPlayer: public SlumsMember
{
Then you can override the getWicketsTaken in this class too

int getWicketsTaken() override;

public: 
   int goalsScored;
   int assists;
   int interceptions;
};

int main() {
   vector<SlumsMember*> members;

请注意，在下一行，如果您给出的值不是贫民窟成员类型，您应该会收到编译器错误。

   members.push_back(new FootballPlayer(rNo,name,gpa,ch,a,b,c));
   members.push_back(new CricketPlayer(rNo,name,gpa,ch,a,b,c));

   SlumsMember *mbr;
   for(int i=0;i<members.size();i++)
   {
      mbr=members[i];
      //How to make sure to which base class an object retrieved belongs to and how to access it.
      int rollNumber = mbr->rollNumber;
      double gpa = mbr->gpa;

等等……并且不要忘记在某个时刻在结束时释放对象，这样就不会出现内存泄漏

      }

   return 0;
}