Variable changing value and unsure of why - c++

Question

So I'm still fairly new to c++ and programming in general, but I'd like to assume that I have a fairly good grasp of the concept and control flow (possibly lol). I'm currently creating a top down style game that allows the user to interact with the inventory of a chest. The problem that has me extremely confused is that I modify a variable but then it changes to something entirely different after "updating" the console.
Interactive chest inventory displaying 10 gold
After pressing s to update the console
The gold amount in the chest is set to 10 in the chestLoot() function, but is then changed to a value of 303, which is the macro for the Healing potion. Why is the chest.gold value being changed to 303 after I set it to 10? Any help on this would be much appreciated. (Don't be too harsh, I'm still new to stack overflow and c++ as well as programming in general)
Here is the code that handles the chest inventory as well as the loot that is generated:
void chestLoot(int x)
{
switch (tutorial.chestIt)
{
case 0:
chest.inventory[x] = WOODEN_SWORD_ID;
break;
case 1:
chest.inventory[x] = GOLD_ID;
chest.gold = 10;
break;
case 2:
chest.inventory[x] = HEALING_POTION_ID;
break;
case 3:
chest.inventory[x] = LEATHER_HELMET_ID;
break;
}
tutorial.chestIt++;
}
void chestInventory()
{
bool endLoop = false;
int x = 0;
int selection = 0;
int highlighted = 0;
while (endLoop == false)
{
system("cls");
std::cout << "Chest:" << std::endl << std::endl;
if (tutorial.gridChestOpened == false)
updatePlayer(5);
for (x = 0; x <= player.level + 3; x++)
{
if (tutorial.gridChestOpened == false)
{
chestLoot(x);
}
switch (chest.inventory[x])
{
case WOODEN_SWORD_ID:
std::cout << x + 1 << ". ";
if (selection == x)
{
std::cout << "- ";
highlighted = selection;
}
std::cout << "Wooden Sword";
break;
case GOLD_ID:
std::cout << x + 1 << ". ";
if (selection == x)
{
std::cout << "- ";
highlighted = selection;
}
std::cout << chest.gold << " Gold";
break;
case HEALING_POTION_ID:
std::cout << x + 1 << ". ";
if (selection == x)
{
std::cout << "- ";
highlighted = selection;
}
std::cout << "Healing Potion";
break;
case LEATHER_HELMET_ID:
std::cout << x + 1 << ". ";
if (selection == x)
{
std::cout << "- ";
highlighted = selection;
}
std::cout << "Leather Helmet";
break;
case NULL:
break;
}
std::cout << std::endl;
}
tutorial.gridChestOpened = true;
switch (_getch())
{
case 'w':
--selection;
if (selection < 0)
selection = 0;
if (chest.inventory[selection] == NULL)
++selection;
break;
case 's':
++selection;
if (selection > tutorial.chestIt)
selection = tutorial.chestIt;
if (chest.inventory[selection] == NULL)
--selection;
break;
case 'e':
if (chest.inventory[highlighted] == 0)
{
std::cout << "There is nothing there";
break;
}
else if (chest.inventory[highlighted] == GOLD_ID)
{
player.gold = player.gold + chest.gold;
chest.inventory[highlighted] = NULL;
break;
}
else
{
for (int y = 1; y <= player.level + 9; y++)
{
if (player.inventory[y] == NULL)
{
player.inventory[y] = chest.inventory[highlighted];
chest.inventory[highlighted] = NULL;
}
}
}
break;
case 27:
endLoop = true;
drawScreen(NULL);
break;
}
}
}
Here are the global variables that are used in the function:
struct Loot
{
int inventory[2];
int gold;
}chest, pot;
struct Entity
{
int position[2] = { 2, 2 };
int gold = 0;
int health = 10;
int level = 1;
int totalXp = 0;
int inventory[11];
int mainHand[2] = {/*location, item*/};
}player/*enemy*/;
struct Grid
{
int grid[6][12] = {
{1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,1,1,1,1,1},
{1,0,0,0,0,2,0,1,0,0,3,1},
{1,0,2,0,0,0,0,1,0,0,0,1},
{1,0,0,0,0,2,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,4,1}
};
bool gridChestOpened = false;
int chestIt = 0;
}tutorial;
// Item ID's
#define WOODEN_SWORD_ID 301
#define GOLD_ID 302
#define HEALING_POTION_ID 303
#define LEATHER_HELMET_ID 304
Any tips on improving my code are much appreciated as well :)
2: Check HerePassing a variable from one function to another

Answer 1

Your problem is that the member inventory of Loot is not dimensioned properly. The only valid values for x in chest.invetory[x] are 0 and 1. Your code is however clearly writing to chest.inventory[2], for example when you call chestLoot(2).
The memory in a struct is laid out sequentially, so chest.inventory[2] = HEALING_POTION_ID; will quietly overwrite the next 4 bytes after the chest.inventory[1] which is chest.gold;

Answer 2

Well, the inventory member of your "loot" struct is an array of ints of length 2. But you seem to be calling "chestLoot" with a value greater than 1. This is causing you to go off the end of your array and write to where "gold" should be.