Array receives two of the same values - c++

Question

Sorry if the code is sloppy, I've only been working with QT for the past couple of weeks. I'm working on a small game while studying, and right now I'm working on when the player buys an item from the shop it will be placed it into the character bag.
The Problem is when I buy the item once, it works fine. But if I delete the item after purchase then repurchase the same item again it will put two of the same item into the array even though I purchased one.
I have 3 files used for this. Inventory.cpp, GameScreen.cpp, Shops.cpp.
GameScreen.cpp is the main file. Here I just initialize everything.
void GameScreen::initGame(QString &characterName, QString &characterProfession){
//PASS CHARACTERNAME AND CHARACTERPROFESSION INTO INVENTORY
inv.initCharacter(characterName, characterProfession);
//INIT BAG
inv.initBag();
//INIT MONEY
inv.initMoney();
//SHOPS INITS
mos.initShop();
mos.passMoneyToShop(inv.gold, inv.silver, inv.copper);
}
This will open the shop window. The Item connect is apart of my problem.
void GameScreen::on_mapOneShopB_clicked()
{
mos.setModal(true);
//SEND THE ITEM INTO BAG
connect(&mos, SIGNAL(getItemFromMapOneShop(const QString&)), &inv, SLOT(bagAddElement(const QString&)));
mos.show();
mos.exec();
}
Moving into Shops.cpp. I use polymorphism in this file and that's the reason why you see MapOneShop:: instead of Shops::. Sorry about the confusion. But moving on, I hit the button and it subtracts the item price from my amount of gold.
void MapOneShop::on_buyB_clicked()
{
//ONLY WORKS IF I HIT THE ITEM NAME COLUMN THEN HIT BUY
gold -= itemPrice[ui->treeWidget->currentColumn()];
//UPDATE INFORMATION
updateInformationVAndMoneyAfterBuy();
}
It then moves into updateInformationVAndMoneyAfterBuy(); which checks that I spent money, and If I did it will emit the item I need. I just emit back to GameScreen.cpp inside of void GameScreen::on_mapOneShopB_clicked() and pass them into Inventory.cpp.
void MapOneShop::updateInformationVAndMoneyAfterBuy()
{
//UPDATE INFORMATIONV FIRST TO CHECK MONEY CHANGES
if(goldCheck != gold)
{
emit getUpdatedMoneyFromShop(gold, silver, copper);
//ITEM NAME IS WHERE I STORE THE NAMES OF THE ITEMS
emit getItemFromMapOneShop(this->itemName[ui->treeWidget->currentColumn()]);
}
}
Now moving into Inventory.cpp. When the item gets passed into bagAddElement after deleting then repurchasing, I get two of the same items even though only 1 should be passed in. I am using a dynamic array for this. Below I will also show the void Inventory::on_deleteB_clicked, void Inventory::bagDeleteAt and also void Inventory::bagLWPrint functions. The items value is my array holding the shopItem strings.
void Inventory::bagAddElement(const QString& shopItem)
{
//I USE THIS TO CHECK THE VALUE shopItem.
qDebug()<<"bagAddElement: " << shopItem;
//IF THE CURRENT POSITION IN THE BAG
//IS BIGGER THAN THE CURRENT SIZE
//IT WILL INCREASE THE BAG FOR US
if(nrOfEl >= bagSize)
{
bagExpand();
}
//CHECK FOR VALUES INSIDE ARRAY AND CHECK IF THEY ARE NULL
//IF SO, IT WILL ADD THE ITEM INTO THE NULL POSITION
for(int i = 0; i < bagSize; i++)
{
if(items[i] == nullptr)
{
nrOfEl = i;
items[nrOfEl++] = shopItem;
break;
}
}
//UPDATE WIDGET LIST
bagLWPrint();
}
Here I pass the currently selected row value inside bagLW and pass it into void Inventory::bagDeleteAt.
void Inventory::on_deleteB_clicked()
{
//BagLW IS A LIST WIDGET
bagDeleteAt(bagLW->currentRow());
}
Now we look for the what's inside items[row] and set it to nullptr. Then we go into void Inventory::bagLWPrint.
void Inventory::bagDeleteAt(int row)
{
if(items[row] == nullptr)
{
//IF THE ITEM IS ALREADY NULL WILL PRINT A MESSAGE
QMessageBox::information(this,"Bag","No item in that slot");
}
else
{
//SET CURRENTLY SELECTED ITEM TO NULL
items[row] = nullptr;
bagLWPrint();
}
}
I clear bagLW and refill it with the updated array.
void Inventory::bagLWPrint()
{
bagLW->clear();
for(int i = 0; i < bagSize; i++)
{
if(items[i] != nullptr)
{
bagLW->addItem(items[i]);
}
if(items[i] == nullptr)
{
bagLW->addItem(items[i]);
}
}
}
Other notes.
-The item only gets doubled when inserted into void Inventory::bagAddElement.
-I tried adding another item inside of void GameScreen::initGame and it did not double after deleting and re-entering.
Sorry for such a long question. And any help would be much, much appreciated.
void Inventory::bagExpand()
{
//1: INCREASE BAGSPACE
bagSize *= 2;
//2: CREATE TEMP ARRAY
QString *tempItems = new QString[bagSize];
//3: COPY OVER VALID VALUES FROM OLD ARRAY
for(int i = 0; i < nrOfEl; i++)
{
tempItems[i] = items[i];
}
//4: DELETE OLD ARRAY MEMORY
delete[] items;
//5: POINT OLD ARRAY POINTER TO NEW ARRAY LOCATION
items = tempItems;
//PRINT BAGLW - (UDPATE)
bagLWPrint();
qDebug()<<"Bag has increased";
}

Answer 1

The problem is that you connect and re-connect the getItemFromMapOneShop signal on every button click. That means that on first click, you add it once (signal triggered, 1 slot connected). On the second click, you add it twice (signal triggered, 2 slots connected). And so on.
QObjects manage a list of all connected slots per signal, and call each of them. Connecting a slot multiple times will call it that many times
You should connect the singal only once, e.g. in the constructor; or disconnect the signal when no longer used
As #Andéon Evain pointed out, you could also use Qt::UniqueConnection. This will not add a duplicate connection if it already exists (considering sender, signal, receiver, slot). That might be useful for cases where it's unknown if already connected; not in your simple case