write, save and read .dat files

[seeplus]

It has to edit and save the items and if there is nothing in the dat file, it needs to ADD them

My latest code above does this. Also, the saveInventory() from that code does work and saves the current inventory which is then read OK when the program is re-started.

Now that we know what options 5) and 6) mean, I'll look into it.

[seeplus]

#include <iostream>
#include <string>
#include <fstream>
#include <iomanip>
#include <limits>
#include <cctype>

constexpr size_t MAX_RECORDS {10};
constexpr size_t SIZE_DESC {20};
const std::string defname {"inventory.dat"};

struct Item {
	char description[SIZE_DESC] {};
	double price {};
	int in_stock {};
	int sold {};
};

Item items[MAX_RECORDS] {};

void createEmptyInventory();
void editInventory();
void displayInventory();
void makeAnOrder();
void createOrderReport();
void createRevenueReport();
void saveInventory(const std::string& fnam = defname);
void readInventory(const std::string& fnam = defname);
void createInventory();
void initInventory();

double getDouble(const std::string& prm = "")
{
	double d {};

	while ((std::cout << prm) && !(std::cin >> d)) {
		std::cout << "Invalid number\n";
		if (prm.empty()) std::cout << "Please re-enter: ";
		std::cin.clear();
		std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
	}

	return d;
}

int getInt(const std::string& prm = "")
{
	int i {};

	while ((std::cout << prm) && !(std::cin >> i)) {
		std::cout << "Invalid number\n";
		if (prm.empty()) std::cout << "Please re-enter: ";
		std::cin.clear();
		std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
	}

	return i;
}

void createEmptyInventory()
{
	char ch {};

	std::cout << "\nWarning! This will destroy all data.\n";
	std::cout << "Press 'y' to continue: ";
	std::cin >> ch;

	if (std::tolower(ch) == 'y') {
		initInventory();
		saveInventory();
	}
}

void createInventory()
{
	size_t itemNo {};

	for (; itemNo < MAX_RECORDS && items[itemNo].description[0]; ++itemNo);

	if (itemNo < MAX_RECORDS) {
		std::cout << "New item " << itemNo + 1 << '\n';
		std::cout << "Enter description: ";
		std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
		std::cin.getline(items[itemNo].description, SIZE_DESC);

		items[itemNo].price = getDouble("Enter Price: ");
		items[itemNo].in_stock = getInt("Enter quantity in stock : ");
		items[itemNo].sold = getInt("Enter quantity sold: ");
	} else
		std::cout << "Inventory full\n";
}

void initInventory()
{
	for (size_t i = 0; i < MAX_RECORDS; ++i) {
		items[i].description[0] = 0;
		items[i].price = 0.0;
		items[i].in_stock = 0;
		items[i].sold = 0;
	}
}


void displayInventory()
{
	std::cout << std::left << std::setw(8) << "\nITEM#" << std::setw(SIZE_DESC + 2) << "DESCRIPTION" << std::setw(8) << "PRICE" << std::setw(11) << "#INSTOCK" << "#SOLD\n";

	for (size_t i = 0; i < MAX_RECORDS; ++i)
		if (items[i].description[0])
			std::cout << std::left << std::setw(8) << i + 1 << std::setw(SIZE_DESC + 2) << items[i].description << std::right << std::setw(5) << items[i].price
			<< std::setw(11) << items[i].in_stock << std::setw(8) << items[i].sold << '\n';
}


void editInventory()
{
	char again {'y'};

	do {
		displayInventory();

		const int itemNo {getInt("Which item # do you want to edit (0 to create, -1 to quit): ") - 1};

		if (itemNo == -2)
			break;

		if (itemNo == -1) {
			createInventory();
			continue;
		}

		if (itemNo < 0 || itemNo >= MAX_RECORDS || items[itemNo].description[0] == 0) {
			std::cout << "Please enter valid item #\n";
			continue;
		}

		std::cout << "1. Description\n";
		std::cout << "2. Price\n";
		std::cout << "3. Quantity In Stock\n";
		std::cout << "4. Quantity Sold\n";
		std::cout << "Enter choice: ";

		switch (getInt()) {
			case 1:
				std::cout << "Enter new description: ";
				std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
				std::cin.getline(items[itemNo].description, SIZE_DESC);
				break;

			case 2:
				items[itemNo].price = getDouble("Enter new Price: ");
				break;

			case 3:
				items[itemNo].in_stock = getInt("Enter new quantity in stock : ");
				break;

			case 4:
				items[itemNo].sold = getInt("Enter new quantity sold: ");
				break;

			default:
				std::cout << "Invalid choice\n";
				break;
		}

		std::cout << "Do you want to edit another record (y/n)? ";
		std::cin >> again;

	} while (std::tolower(again) == 'y');

	saveInventory();
}

void makeAnOrder()
{
	while (true) {
		displayInventory();

		const int itemNo {getInt("Which item # do you want to order (-1 to quit): ") - 1};

		if (itemNo == -2)
			break;

		if (itemNo < 0 || itemNo >= MAX_RECORDS || items[itemNo].description[0] == 0) {
			std::cout << "Please enter valid item #\n";
			continue;
		}

		std::cout << "Description: " << items[itemNo].description << '\n';
		std::cout << "Price: " << items[itemNo].price << '\n';
		std::cout << "Quantity In Stock: " << items[itemNo].in_stock << '\n';
		std::cout << "Quantity Sold: " << items[itemNo].sold << '\n';

		const int qty {getInt("How many? ")};

		if (qty > items[itemNo].in_stock)
			std::cout << "Sorry, your order exceeds number in stock.\n";
		else {
			items[itemNo].in_stock -= qty;
			items[itemNo].sold += qty;
			std::cout << "Amount due: " << items[itemNo].price * qty << '\n';
		}
	}
	saveInventory();
}

void createOrderReport()
{
	std::cout << "\nItems to reorder\n\n";
	std::cout << std::left << std::setw(8) << "ITEM#" << std::setw(SIZE_DESC + 2) << "DESCRIPTION" << std::setw(8) << "PRICE" << std::setw(11) << "#INSTOCK" << "#SOLD\n";

	for (size_t i = 0; i < MAX_RECORDS; ++i)
		if (items[i].description[0] && items[i].in_stock <= 5)
			std::cout << std::left << std::setw(8) << i + 1 << std::setw(SIZE_DESC + 2) << items[i].description << std::right << std::setw(5) << items[i].price
			<< std::setw(11) << items[i].in_stock << std::setw(8) << items[i].sold << '\n';
}

void saveInventory(const std::string& fnam)
{
	const std::string fn {fnam.empty() ? defname : fnam};

	std::ofstream outfile(fn, std::ios::binary);

	if (outfile.is_open())
		if (outfile.write((char*)&items, sizeof(items)))
			std::cout << "Wrote data file " << fn << " OK\n";
		else
			std::cout << "Problem writing data file " << fn << '\n';
	else
		std::cout << "File opening error for " << fn << '\n';
}

void readInventory(const std::string& fnam)
{
	const std::string fn {fnam.empty() ? defname : fnam};

	std::ifstream infile(fn, std::ios::binary);

	if (infile.is_open())
		if (infile.read((char*)&items, sizeof(items)))
			std::cout << "Read data file " << fn << " OK\n";
		else
			std::cout << "Problem reading data file " << fn << '\n';
	else
		std::cout << "Input file does not yet exist " << fn << '\n';
}

int main()
{
	readInventory();

	while (true) {
		std::cout << "\n   ORCHARD TO TABLE ORDERING SYSTEM \n\n";
		std::cout << "1. Create Empty Inventory\n";
		std::cout << "2. Display State of Inventory\n";
		std::cout << "3. Edit/Create Inventory\n";
		std::cout << "4. Make an Order\n";
		std::cout << "5. Create Reorder Report\n";
		std::cout << "6. Create Revenue Report\n";
		std::cout << "7. Save Current Inventory\n";
		std::cout << "8. Load New Inventory\n";
		std::cout << "9. Quit \n";

		std::cout << "Enter your choice: ";

		switch (getInt()) {
			case 1:
				createEmptyInventory();
				break;

			case 2:
				displayInventory();
				break;

			case 3:
				editInventory();
				break;

			case 4:
				makeAnOrder();
				break;

			case 5:
				createOrderReport();
				break;

			case 6:
				break;

			case 7:
				{
					std::string name;

					std::cout << "\nFile name to save to [" << defname << "] :";
					std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
					std::getline(std::cin, name);

					saveInventory(name);
				}
				break;

			case 8:
				{
					std::string name;

					std::cout << "\nFile name to load from [" << defname << "] :";
					std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
					std::getline(std::cin, name);

					saveInventory();
					initInventory();
					readInventory(name);
				}
				break;


			case 9:
				return 0;

			default:
				std::cout << "Invalid choice\n";
				break;
		}
	}
}

[seeplus]

Changes above (have to separate due to post size limitations):

1) Can save to a specified file
2) New option to load from a specified file
3) Data updates automatically save the data file to default name
4) Option 5) added

re option 6)

for createRevenueReport()
I need to generate a Revenue report which tells us how much we have made on each of the items that we carry.

What is meant by 'how much we have made on each of the items' ? Is this simply numsold * price?