Adding elements to an array?

[TheJabre]

Hi. I'm trying to make a sort of text "shop". Here's the code:

#include <iostream>
#include <cmath>
using namespace std;
void Shop(int);

int Gold = 10;

int HealthPotion = 0;
int ManaPotion = 0;

int Choice;
string Inventory[5];


int main(){



cout << "You are in the shop. What would you like to buy?";
cout << " You have " << Gold << " gold.";
cout << endl;
cout << "1\) Health potion: 2 gold.  2\) Mana Potion: 3 gold.";
cin >> Choice;
Shop(Choice);

cin.ignore();
cin.get();
return 0;
}

void Shop(int x){
 if(x==1){
   HealthPotion++;
   Gold = Gold-2;
   }
 if(x==2){
   ManaPotion++;
   Gold = Gold-3;
   }

}

All that works just fine. What I want to do is if they buy something, it adds it to the next available element in the array "Inventory". Basically if I buy a Health Potion and my inventory is empty, it becomes Inventory[0].

I have NO idea how to do this and the google searches I've done have come up empty or with over-complicated information.

Can someone please explain to me how to do this?

[Athar]

The number of elements in an array is always fixed, you cannot change it.
That's what vectors are for:
http://www.cplusplus.com/reference/stl/vector/

[Albatross]

Probably the easiest way to do this is to use an std::vector.

Here are some side-by-side comparisons of arrays and std::vectors:

//Constant-size array
//Initialize
type name[size];
//Access an element
name[position];
//Resize
//Impossible if you use the name[size] syntax.
//Get the size:
//It's best to store it in a variable. 

//Vector
//Initialize
std::vector<type> name(size);
//Access an element
name[position];
//Resize
name.resize(new_size);
//Get the size:
name.size();

EDIT: Samurai'd.

-Albatross

[atropos]

If you want each purchase to be assigned to the first empty element of the array, you need to have a variable that keeps track of the current number of items already in the inventory int itemsInInventory;. That way, when you buy an item, you can add the line ++itemsInInventory; and when you remove an item,
--itemsInInventory.

[z0RDjE8b]

It's easy just do this:

string Caga[3];
Caga[0] = "S";
Caga[1] = "H";
Caga[2] = "O";
Caga[3] = "P";

[BHX]

Actually it would be:

 
char Caga[4];
Caga[0] = 'S';
Caga[1] = 'H';
Caga[2] = 'O';
Caga[3] = 'P';

Your code would only hold SHO and is using an overkill data type as string Caga[3] would make it so you could do:

string Caga[3]; 
Caga[0] = "SHOP";
Caga[1] = "SHOP";
Caga[2] = "SHOP";

[atropos]

@BHXSpecter: If you stop feeding it, it will die of starvation

[BHX]

@atropos: Just didn't want TheJabre to believe BooleanBoy's wrong code. Though, I stopped looking at the new user posts as I've grown tired of the trolling. I assumed Jabre was a real new user and was just warning on the bad code.

Not meaning to feed the troll.

[atropos]

Ah, I never thought of that possibility. I just assumed that you replied to his/her/its/their post because you took the bait, so to speak; now I see that it was done to correct his/her/its/their subscript range error. Sorry I jumped the gun like that.

He/she/it/they have some people on edge and/or exasperated ATM.
like me

[IceThatJaw]

This dinky little program screams Object Oriented to me.

Customer class has an Inventory class and boom! Your code will be so sexy. lol

class Inventory
{
	public:
	bool AddItem(int item)
	{
		bool purchased = true;
		switch (item)
		{
			case 0: inventory.push_back('H');
				break;
			case 1: inventory.push_back('M');
				break;
			default:
				purchased = false;
		}
		return purchased;
	}

	void Write(ostream& out) const
	{
		for (int i = 0; i < inventory.size(); i++)
			out << inventory[i] << " "; 
	}
	private:
	vector<char> inventory;
};

int main() 
{
	
	Inventory myInventory;

	myInventory.AddItem(0);
	myInventory.AddItem(1);
		
	myInventory.Write(cout);

	return 0;

};

I would actually use enums and valid a bit more but this is how I would approach it.

TS, look into Object Oriented Programming because it's awesome and will save you the stress of procedural programming. It's not the be all-end all of programming but it helps in most situations where you want more readable code and instead of absolute performance.

[BHX]

@atropos It's okay, though for fun I ran BooleanBoy's code but changed string to char:

#include <iostream>
using namespace std;

int main()
{
	char Cage[3];
	Cage[0] = 'S';
	Cage[1] = 'H';
	Cage[2] = 'O';
	Cage[3] = 'P';
	
	for (int i = 0; i < 4; i++)
	{
		cout << Cage[i] << ' ';
	}
	cout << endl;
	return 0;
}

And got this output:

S H O ♥

Don't know what everyone will see but in my test it printed SHO and then a heart. Soon as I saw it I thought "The app is showing SHO Love (Sure love)." lol

[long double main]

Because:
char Cage[3];
only goes from Cage[0] to Cage[2].

If you write to anything beyond that, you may get...unexpected results.

[BHX]

I know, just love the 'unexpected results' being a heart.

[IceThatJaw]

I ♥ how none of us actually gave the TS a straight answer to his question. I just can't stomach explaining array like that. It's the reason why I can never be a teacher, even though both of my parents were. haha

[ui uiho]

vectors were suggested otherwise you can do a dynamically allocated array or use pointers to change the allocated memory sections which the array covers, extending it size,

myvector.push_back(/*puts this at end of container*/)

that is the easiest way to do it.

[BHX]

I ♥ how none of us actually gave the TS a straight answer to his question. I just can't stomach explaining array like that. It's the reason why I can never be a teacher, even though both of my parents were. haha

Albatross gave them a straight answer. Vectors is the best way to do it with push_back() as ui-uiho just pointed out.

[atropos]

I think TS wanted to store an item in the first empty element of the array, not dynamically resize the array.

TheJabre wrote:

What I want to do is if they buy something, it adds it to the next available element in the array "Inventory". Basically if I buy a Health Potion and my inventory is empty, it becomes Inventory[0].

..which I interpreted as: If I buy something, and the inventory is empty, the thing I bought is stored in the first element of the array. If I buy something and already have two items in Inventory, the thing I bought is stored in the third element of the array.

That leads me to think the TS needs a variable to keep track of the current first empty element of the array, and use this variable as the array subscript to store new items or remove them.

[TheJabre]

Okay. Confusion confusion lol.

Someone mentioned vectors and I researched that in the C++ books I have and bam, I have a working script. Thanks to everyone who tried to help!