Question

Hey i set up a header and a .cpp file for my inventory. Im using a vector. I cant use anyof the push/ or pop methods that come in the vector library. I want to use them in the main. Also i am gettin 3 errors to do with the add method i made so that i could add to the vector in the main.

Can anyone help me to understand why i cant use the vectors functions and why i am getting these errors.

Here is my code:
Inventory.h

 #ifndef INVENTORY_H
    #define INVENTORY_H
    #include <string>


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

    //Methods.
    std:: string add(string item);
    void displayInventory();
    void showInventory();
private:
    //Data members
    };


#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;
vector<string> inventory;
vector<string>::iterator myIterator;
vector<string>::const_iterator iter;


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;
}

Errors

Error   1   error C2061: syntax error : identifier 'string' c:\users\conor\documents\college\dkit - year 2 - repeat\dkit - year 2 - semester 1 - repeat\games programming\maroonedca2\maroonedca2\inventory.h   17  1   MaroonedCA2
Error   2   error C2061: syntax error : identifier 'string' c:\users\conor\documents\college\dkit - year 2 - repeat\dkit - year 2 - semester 1 - repeat\games programming\maroonedca2\maroonedca2\inventory.h   17  1   MaroonedCA2
Error   3   error C2511: 'std::string Inventory::add(std::string)' : overloaded member function not found in 'Inventory'    c:\users\conor\documents\college\dkit - year 2 - repeat\dkit - year 2 - semester 1 - repeat\games programming\maroonedca2\maroonedca2\inventory.cpp 19  1   MaroonedCA2

Answer 1

Your issue is in the header, and you lack of using namespace std. I never, ever use this command. I think it’s must better to be explicit with your namespaces, and you will avoid issues like this.

// Compiler knows what std::string is, but not string on it's own.
std:: string add(string item);

If it was my project, I would remove the using namespace std and use std:: everywhere.

Furthermore, you’re not using your class properly. You have member methods that are operating on global variables in the .cpp file.

vector<string> inventory;

Should be a a private member of the Inventory class.

Iterarors

To address your comments, what I’m trying to say is that you don’t need to declare iterators like that to use them, unless you need to store an iterator for later use (for some reason. Although can be dangerous when iterators are invalidated). Here are a few ways you can use them.

typedef

Using typedefs makes your life easier.

typedef std::vector<std::string> StringVec;
typedef StringVec::iterator StringVecIter;

Now you can use them in loops.

for(StringVecIter it = inventory.begin(); iter != inventory.end(); ++it)
{ ... }

auto

An easier way to do these loops, is with the auto keyword. The compiler assign the appropriate type to the variable, which in this case is std::vector<std::string>::iterator

for(auto it = inventory.begin(); it != inventory.end(); ++it)
{ ... }