C++ linked list/polymorphism not running list function -

i have make class shape subclasses specific shapes find volume. have able construct objects , store them in linked list. testing creating 1 object , wondering why not run function cout commands. appreciated. thanks

#include <iostream> #include <array>  using namespace std;  class shape{ public:     friend class my_list;     shape(double a=0,double b=0 ,double c=0):width(a),height(b),length(c){     }  protected:     double width;     double height;     double length;     shape *nextptr; };  class rectangle:public shape { public:     rectangle(double a, double b,double c):shape(a,b,c){         area = width * length;     };  private:     double area; };  class circle:public shape { public:     circle(double a):shape(a){         area = (radius*radius)*3.14;     } protected:     double area;     double radius; };  class triangle:public shape { public:     triangle(double a, double b,double c):shape(a,b,c){         area = .5*width*length;     }; protected:     double area; };  class cubic:public rectangle { public:     cubic(double a, double b,double c):rectangle(a,b,c){         volume = width * length * height;     }; protected:     double volume; };  class sphere:public circle { public:     sphere(double a):circle(a){         volume = (width*width*width)*(4/3)*3.14;     }; protected:     double volume; };  class cone:public circle{ public:     cone(double a, double b):circle(a){         height = b;         volume = 3.14*(width*width)*(height/3);     }; protected:     double volume; };  class my_list{ public:     my_list();     ~my_list();      void add_node(shape*);     void print_list();     shape* make_node();  private:     shape* firstptr;     shape* lastptr; };  my_list::my_list():firstptr(null), lastptr(null){} my_list::~my_list(){}  shape* my_list::make_node(){     cout << "what shape construct?" << endl;     cout << "\t1. rectangle" << "\n\t2. triangle" << "\n\t3. cirlce" <<     "\n\t4. cubic" <<"\n\t5. sphere" << "\n\t6. cone" << endl;     int number; cin >> number; cin.get();      cout << "enter width/height/length or radius, or radius/height" << endl;     double a,b,c; cin >> a; cin>>b; cin>> c;     switch (number) {         case 1: {             shape *newptr = new rectangle(a,b,c);             return newptr;         }          case 2: {             shape *newptr = new triangle(a,b,c);             return newptr;          }          case 3: {             shape *newptr = new circle(a);             return newptr;         }         case 4: {             shape *newptr = new sphere(a);             return newptr;         }         case 5: {             shape *newptr = new cubic(a,b,c);             return newptr;         }          case 6:{             shape *newptr = new cone(a,b);             return newptr;         }         default:                return 0;     } }  void my_list::add_node(shape* new_node){     if ( firstptr == null ) // empty list         firstptr = lastptr = new_node; // nextptr  = null default     else {         new_node -> nextptr = firstptr;         firstptr = new_node; // set first pointer beginning of list;     } }  int main(){     /*     while(true) {         cout << endl << endl << "\tselect following options" << endl;         cout << "\t1. construct" << "\n\t2. add" << "\n\t3. print" <<         "\n\t4. quit" << endl;         cout << "\tselection:\t";         int options; cin >> options; cin.get(); // cin leaves newline, cin.get() cancel          switch (options) {             case 1: //construct function              case 2: {               //add function             }              case 3:                //print function                case 4:             default: break;         }     }     */      my_list l1;     l1.add_node(l1.make_node()); } 

few pointers :

1. try creating object of my_list before calling functions on . my_list l1 = new my_list();

2. in switch-case usage use break instead of return. like:

   switch (n){ case 1: ... break;

   case 2: ... break; }

3.start using ide , add break points debugging.