Inventory Class problems

[Orca239]

For this program, I have to create an Inventory class with the private member variables itemNumber, quantity, cost, and totalCost. I have to have public functions including a default constructor, a second constructor that accepts itemNumber, quantity, and cost as arguments; mutators; and accessors. Then I have to write a simple program that demonstrates the class.

Here are the files:

Problem 13.cpp

#include "Inventory.h"
#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
	int itemNumber,
		quantity;
	double cost,
		   totalCost;

	cout << "Enter the Item Number: ";
	cin >> itemNumber;
	while (itemNumber < 0)
	{
		cout << "Error - Enter a positive value for the Item Number: ";
		cin >> itemNumber;
	}
	cout << "Enter the Quantity of the item: ";
	cin >> quantity;
	while (quantity < 0)
	{
		cout << "Error - Enter a positive value for the Quantity of the item: ";
		cin >> quantity;
	}
	cout << "Enter the Cost of the item: $";
	cin >> cost;
	while (cost < 0)
	{
		cout << "Error - Enter a positive value for the Cost of the item: $";
		cin >> cost;
	}

	cout << "----------------------------------" << endl;

	Inventory inventoryA(itemNumber, quantity, cost);

	totalCost = inventoryA.getTotalCost();
	itemNumber = inventoryA.getItemNumber();
	cost = inventoryA.getCost();
	quantity = inventoryA.getQuantity();
	cout << "Item Number: " << itemNumber << endl;
	cout << "Quantity: " << quantity << endl;
	cout << "Cost: $" << cost << endl;
	cout << "Total Cost: $" << fixed << setprecision(2) << totalCost << endl << endl;
	
	return 0;
}

Inventory.h

#ifndef INVENTORY_H
#define INVENTORY_H

class Inventory
{
	private:
		int itemNumber,
			quantity;
		double cost,
			   totalCost;
	public:
		Inventory()
		{
			itemNumber = 0;
			quantity = 0;
			cost = 0;
			totalCost = 0;
		}
		Inventory(int itemNumber, int quantity, double cost)
		{
			itemNumber = getItemNumber();
			quantity = getQuantity();
			cost = getCost();
			setTotalCost(quantity, cost);
		}

		void setItemNumber(int)
		{
			itemNumber = itemNumber;
		}
		void setQuantity(int)
		{
			quantity = quantity;
		}
		void setCost(double)
		{
			cost = cost;
		}
		void setTotalCost(int, double)
		{
			totalCost = quantity * cost;
		}

		int getItemNumber()
		{
			return itemNumber;
		}
		int getQuantity()
		{
			return quantity;
		}
		double getCost()
		{
			return cost;
		}
		double getTotalCost()
		{
			return totalCost;
		}
};
#endif 

The output I get always shows some really random numbers, such as 7883933849400000000000000.00 or something for the totalCost.

It's probably something really stupid on my part, but I can't see what I've done... any help would be really appreciated.