Polymorphism constructor function - c++

Question

My code compiles fine but I am having issues with a particular section not displaying the correct output.
Here is my base class
class Item
{
protected:
//int count;
string model_name;
int item_number;
public:
Item();
Item(string name, int number);
string getName(){return model_name;}
int getNumber(){return item_number;}
and here is my derived class:
class Bed : public Item
{
private:
string frame;
string frameColour;
string mattress;
public:
Bed();
Bed(int number, string name, string frm, string fclr, string mtres);
Function definitions:
Bed::Bed(int number, string name, string frm, string fclr, string mtres)
{
model_name=name;
item_number=number;
frame=frm;
frameColour=fclr;
mattress=mtres;
cout<<model_name<<item_number<<frame<<frameColour<<mattress<<endl;
}
Main section that is causing the problem:
Item* item= new Bed(number, name, material, colour, mattress);
cout<<"working, new bed"<<endl;
v.push_back(item);
cout<<"working pushback"<<endl;
cout<<" this is whats been stored:"<<endl;
cout<<v[count]->getName<<endl;
cout<<v[count]->getNumber<<endl;
count++;
when the programme executes, the cout within the constructor shows the correct output, but when I call getname and getnumber from the main function the programme prints '1' for both , no matter what's stored in there.
I thought that derived classes could use base class methods, what have I missed?
Any help would be great
thanks
Hx

Answer 1

Well, you example is not related to polymorphism. The reason here is that you are not using any virtual functions. Here is the code that you can use.
class Item
{
protected:
std::string model_name;
int item_number;
public:
Item();
Item(std::string& name, int number) : model_name(name), item_number(number) {};
std::string getName(){return model_name;}
int getNumber(){return item_number;}
};
class Bed : public Item
{
private:
std::string frame;
std::string frameColour;
std::string mattress;
public:
Bed();
Bed(int number, std::string& name, std::string& frm, std::string& fclr, std::string& mtres) : Item(name, number),
frame(frm),
frameColour(fclr),
mattress(mtres) {};
};
int main()
{
int count = 0;
std::vector<Item*> v;
Item* item = new Bed(2, std::string("MyBed"), std::string("wood"), std::string("red"), std::string("soft"));
std::cout << "working, new bed" << std::endl;
v.push_back(item);
std::cout << "working pushback" << std::endl;
std::cout << " this is whats been stored:" << std::endl;
std::cout << v[count]->getName() << std::endl;
std::cout << v[count]->getNumber() << std::endl;
++count;
getchar();
}

Answer 2

This looks incorrect (and I am unsure how this even compiled):
cout<<v[count]->getName<<endl;
cout<<v[count]->getNumber<<endl;
as getName and getNumber are methods. Change to:
cout<<v[count]->getName()<<endl;
cout<<v[count]->getNumber()<<endl;
Additionally, the initialisation of count is not posted: ensure it is zero.

Answer 3

count appears to be the size of your vector. After you push back the last element, you're not incrementing count, so you're printing an older element.
Why don't you try:
cout<<v[v.size()-1]->getName<<endl;
cout<<v[v.size()-1]->getNumber<<endl;
Also, you should start using initialization lists in your constructors:
Bed::Bed(int number, string name, string frm, string fclr, string mtres) :
Item(name,number),
frame(frm),
frameColour(fclr),
mattress(mtres)
{
}

Answer 4

You have not called the base class's constructor from the derived class... Where as it should be the first line... update the code, I am sure it will start working..
EDIT
If it doesn't than you should probably also check the way you are handling count variable... as pointed out by others..