RPG inventory, removing items

So I have a basic Inventory system:

Code:

---

typedef struct sitem
{
    string name; // A short name for the item
    string description; // A description of item
}
sitem;



sitem sword = {
                  "Sword", "A big heavy sword."
              };
             
sitem longsword = {
                      "Longsword", "A huge Long Sword!"
                  };
                 
sitem poop = {
                "Poop", "A piece of poop"
            };
           



int main()
{
    std::vector<sitem> inventory;
    inventory.push_back(longsword); // adds a longsword
    inventory.push_back(sword); // adds a sword
    inventory.push_back(poop); // adds a piece of poop
   
   
    for (std::vector<sitem>::const_iterator i = inventory.begin(); i != inventory.end(); ++i)
    {
        if (sword.name == "Sword")
        {
      //  i = inventory.erase();
        }
    }
   
    for (std::vector<sitem>::const_iterator i = inventory.begin(); i != inventory.end(); ++i)
    {
        std::cout << i->name << "\t" << std::endl << '\t' << i->description << endl;
    }
   
    return 0;
   
}

---

With this I am able to add items to the players inventory, but I don't know how to remove items. If I un-comment the orange line i get the following compiler error:

" no matching function for call to `std::vector<sitem, std::allocator<sitem> >::erase()' "

I would just like to be able to remove any given item in the inventory, I might have to add an id for each current item in there as well.

inventory.erase(i);

I tried that, but i get this error:

609 C:\Dev-Cpp\include\c++\3.4.2\bits\stl_iterator.h invalid conversion from `const sitem* const' to `sitem*'

ah, remove the const_interator and replace it by iterator

if you are just reading the items, use the const_iterator
if you are modifying them use iterator.

of course, a object referred via a const iterator cannot be removed (otherwise it would violate the constness)

Thanks a lot.

Oh and btw, would anybody know how to add an id thing for the inventory when I can run a remove item function with the id number? Just wondering..

Instead of a vector, use a map if the IDs will be unique or a multimap if not. One advantage is that you will not need to iterate through the container to find or delete elements.

Overload your remove function so you can pass it a name or a number. I'd suggest using your own class for objects, and making it a bit more generic. Your remove function would just be a "remove from what contains me" function. "Inventory" would just be an object that stores other objects.

Or not.


Quzah.

Honestly, I'm not to great with maps. So far I fixed up to the orange line, I'm not sure what to do with the display() and remove() functions (I will do the function overload thing later)

Code:

---

void add(sitem stuff);
void displaythings();
void remove(int number);
map<sitem, int> inventory;
int amount;

int main()
{

    add(sword);
    add(poop);
    add(longsword);
    cout << amount;
    poop.id = 2;
    //remove (0);
    displaythings();
   
   
   
    system("Pause");
    return 0;
   
}


void add(sitem stuff)
{
    inventory.insert( make_pair(stuff, 5));

}

--------------------------------------------------------

void displaythings()
{
    for (:map<sitem, int>::iterator i = inventory.begin(); i != inventory.end(); ++i)
    {
        std::cout << '(' << i->id << ')' << i->name << "\t" << std::endl << '\t' << i->description << endl;
    }
}

void remove(int number)
{

    for (std::map<sitem, int>::iterator i = inventory.begin(); i != inventory.end();)
    {

        if (i->id == number)
        {
            i = inventory.erase(i);
            break;
        }
    }
}

---

maps offer specific functions you can use to access and change/delete elements based on the key. You don't need to build for loops to search and delete an item. It's much easier than that.

Here's a tutorial on maps: http://www.cprogramming.com/tutorial/stl/stlmap.html
And here is another one: http://cplus.about.com/od/stltutorial/l/aa120103e.htm

Thanks

Code:

---

typedef struct sitem
{
    string name; // A short name for the item
    string description; // A description of item
    int id;
}
sitem;

sitem sword = {
                  "Sword", "A big heavy sword."
              };
           

void add(sitem stuff);
map<sitem*,int> inventory;


int main()
{

  add(sword);
    return 0;
}


void add(int stuff)
{
   
    inventory.insert ( make_pair (const stuff, 18 ) );

}

---

If I change the map to something other than the sruct "sitem", it works (int, string ect..). I just can't get it to insert a typedef'ed struct!

You add items by using std::make_pair() or creating the pair manually.

In this snippet from my tile manager class you will see that I'm adding an object to the end of the list. This map is:

std::map<DWORD,CTileGDI *> m_mapTiles;

It uses DWORDs or 32-bit unsigned integers and to access CTileGDI objects. The DWORD can either be assigned, in which case if it is assigned an already existing DWORD, they are swapped - or you can use the following Add() which simply adds the item to the end of the map, assigning it a DWORD representing the current size of the map.

Code:

---

void CTileMgrGDI::Add(CTileGDI *pTile)
{
  if (!m_bInit) return;
 
  pTile->m_dwID=static_cast<DWORD>(m_mapTiles.size());
 
  m_mapTiles.insert(std::make_pair( static_cast<DWORD>(m_mapTiles.size()),
                                    (CTileGDI *)pTile));
                                   
 
}

---

I'm casting map::size() to a DWORD to avoid the warning resulting from size() returning size_t instead of DWORD.