Access to the iterator,vector in the Inventory.h

Question

Hey im using a vector plus its iterator. I have it in the Inventory.h file along with the Inventory.cpp. I want to know is can i call it directly so i can get access to the vector library functions such as push,pop etc... Because at the moment i cant. Can someone help me with this.

Here is my code:

Inventory.h

//-------------------------------------------------------------------------------
//  Inventory.h
//-------------------------------------------------------------------------------

#ifndef INVENTORY_H
#define INVENTORY_H
#include <string>
#include <vector>

using namespace std; 
class Inventory
{
public:
    //Constructor
    Inventory();

    //Methods.
    string add(string item);
    void displayInventory();
    void showInventory();
private:
    //Data members
   vector<string> inventory;
   vector<string>::iterator myIterator;
   vector<string>::const_iterator iter;
    };


#endif //INVENTORY_H

Inventory.cpp

#include "Inventory.h"
#include <iostream>
#include <vector>   //  To enable the use of the vector class.
#include <string>


using namespace std;



Inventory::Inventory()
{

}

string Inventory :: add(string item)
{
inventory.push_back(item);
return item;
}

void Inventory:: showInventory()
{
char input[80];
    cin >> input;
    char inventoryRequest[] = "i";
    int invent = strcmp (input,inventoryRequest);
    //compare the player input to inventoryRequest (i) to see if they want to look at inventory.
    if(invent == 0)
    {
        displayInventory();
    }


}
void Inventory:: displayInventory()
{
//vector<string> inventory;
    cout<< "You have " << inventory.size() << " items.\n";
    cout << "\n******Inventory******";
    cout<< "\nYour items:\n";
    for (int i= 0; i< inventory.size(); ++i)
        cout<< inventory[i] << endl;
}

What i want to be able to do:

int main()
{
Inventory inventory;
inventory.push_back();


}

Errors

Error   2   error LNK2019: unresolved external symbol "public: class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > > & __thiscall Inventory::GetContainer(void)" (?GetContainer@Inventory@@QAEAAV?$vector@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@@std@@XZ) referenced in function _main   C:\Users\Conor\Documents\College\DKIT - Year 2 - Repeat\DKIT - Year 2 - Semester 1 - Repeat\Games Programming\MaroonedCA2\MaroonedCA2\Main.obj  MaroonedCA2
Error   3   error LNK1120: 1 unresolved externals   C:\Users\Conor\Documents\College\DKIT - Year 2 - Repeat\DKIT - Year 2 - Semester 1 - Repeat\Games Programming\MaroonedCA2\Debug\MaroonedCA2.exe MaroonedCA2

Answer 1

You can inherityour class from std::vector:

class Inventory : public std::vector<std::string> {
   public:
      Inventory();
      void displayInventory();
      void showInventory();
      // [...] 
}

Then in your code you should be able to do things like:

int main()
{
    Inventory inv;
    inv.push_back("item 1");
    inv.push_back("item 2");
    for (Inventor::iterator it = inv.begin(); it != inv.end(); ++it)
           std::cerr << *it << ' ';
    std::cerr << std::endl;
}

Through inheritance you can avoid to redefine methods, iterators and so on.

Answer 2

A simple solution is to add a push_back and the other vector methods you want to replicate to your inventory class:

class Inventory
{
public:
    //Constructor
    Inventory();

    //Methods.
    std::string add(std::string item);
    void displayInventory();
    void showInventory();
    void push_back(const std::string& s) { inventory.push_back(s); }
private:
    //Data members
   std::vector<std::string> inventory;
   std::vector<std::string>::iterator myIterator;
   std::vector<std::string>::const_iterator iter;
};

Note that inheriting privately from std::vector could also be an option. It is not 100% safe, but it is hard to find scenarios where it could pose a problem. Inheriting publicly is a definite no-no. This example shows how to expose part of std::vector's privately inherited public interface:

class Inventory : private std::vector<std::string>
{
 public:
  // make a selection of the vector's methods public for this class.
  using std::vector<std::string>::push_back;
  using std::vector<std::string>::pop_back;
  using std::vector<std::string>::begin;
  using std::vector<std::string>::end;
};

Answer 3

There are many issues/improvement areas with this code snippet. However, for the specific one you asked, please note that 'push_back' is not a member function of Inventory class. So you are getting the compiler error.

You need to call inventory.add for this.