question about the end of my code

[utahkaratekid]

Write your question here.
I cannot figure out why my code is giving me a negative amount of tender due at the end of the program... can anyone help?

  #include <iostream>

#include <iomanip>
using namespace std;
void showMenu();

void displayBill(float bill, float totalBill, float& tip, float& taxDue);

void displayChange(float amtTendered, float amtChangeDue);

float bill, totalBill, amtTendered, amtChangeDue, taxDue, tipDue;

int main()

{
	//constants for menu items

	const int hamburgerPrice = 6;

	const float hotdogPrice = 4.5;

	const float peanutsPrice = 3.75;

	const float popcornPrice = 5.5;

	const float sodaPrice = 2.8;

	const int chipsPrice = 1;

	const int waterPrice = 2;

	//tax constant

	const float tax = 0.054;

	const float tip = 0.20;

	//total variables

	char menuChoice;

	float bill = 0;

	void showMenu();

	{

		cout << "Baseball Game Snack Menu" << endl;

		cout << "1 - hamburger    $6.00" << endl;

		cout << "2 - Hotdog       $4.50" << endl;

		cout << "3-  Peanuts      $3.75" << endl;

		cout << "4 - Popcorn      $5.50" << endl;

		cout << "5 - Soda         $2.80" << endl;

		cout << "6 - Chips        $1.00" << endl;

		cout << "7 - Water        $2.00" << endl;

		cout << "8 - END ORDER" << endl;

	}



	cout << "Enter menu item: \n";

	cin >> menuChoice;

	do
	{
		switch (menuChoice)
		{

		case '1':

			bill = bill + hamburgerPrice;

			cout << "Enter menu item: \n";

			cin >> menuChoice;
			break;
		case '2':
			bill = bill + hotdogPrice;
			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;

		case '3':

			bill = bill + peanutsPrice;

			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;

		case '4':

			bill = bill + popcornPrice;

			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;

		case '5':

			bill = bill + sodaPrice;

			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;

		case '6':

			bill = bill + chipsPrice;
			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;

		case '7':

			bill = bill + waterPrice;

			cout << "Enter menu item: \n";

			cin >> menuChoice;

			break;
		case '8':

			exit(0);

		default:

			cout << "You did not enter a menu item! (1-8):";

			cin >> menuChoice;

			break;
		}
	} while (menuChoice < '8');

	void displayBill(float& bill, float totalBill, float& tip, float taxDue);
	{

		float taxDue = bill * tax;

		float tipDue = bill * tip;

		float totalBill = bill + taxDue + tipDue;8

		cout << setprecision(3) << "Bill = $" << bill << endl;

		cout << "Tax = " << taxDue << endl;

		cout << "Tip = " << tipDue << endl;

		cout << setprecision(3) << "Total amount due: $" << totalBill << endl;

	}
	void displayChange(float& amtTendered, float amtChangeDue);
	{

		cout << "Enter Amount Tendered: " << endl;
		cin >> amtTendered;

		if (amtTendered < (bill + tip + tax))

		{
	cout << "Please enter enough to cover total bill" << endl;

			cin >> amtTendered;
		}

		else

		{
			amtChangeDue = totalBill - amtTendered;
			cout << "Change Due: $" << amtChangeDue << endl;
		}
	}
	system("pause");
		return 0;
}

[Repeater]

You mean this?
amtChangeDue = totalBill - amtTendered;

What was the totalBill value, and what was the amtTendered value?

If amtTendered is bigger than totalBill , it seems pretty obvious why amtChangeDue is negative; if you have a number, and you subtract from it a bigger number, the result is negative.