c++ vector type function implemetation :     class City
    {
       private:
       int id;
       string name;
       int populations;
    int nooftourist;
    vector<Attraction*>&attractions;
    public:
        City(int id,string name,int populations,int        nooftourist):id(id),name(name),populations(populations),nooftourist(nooftourist){}
     void setId(int _id);
    void setName(string _name);
    int getId();
    string getName();
    void display(){}
    vector<Attraction*>getAttractions() { return attractions;}

};

what wrong with my program,i dont understand the vector type function
