Help with c++ program

19 Dec 2003

      I'm currently trying to improve my knowledge of C++ and writing as many programs as I can. My latest program has given me a problem and I can't seem to overcome it.

My initial program has come from a book I was reading and I am building on it to add more features. 
It consists of a an ordering system using structures for stock.

At present everytime I start the program I have to populate the stock from scratch. Idealy I want to save the stock onto disk and load it everytime the program starts.

I am starting by populating by hand and then saving this to disk as I assumed this would be the easier bit, however I am having a little troube with this function.

After this, I am proposing to load the file back into the program within the structures and need help with this too although I have not yet made a start on this function.

I have search all my books and the net, but am strugling to find information to help me with this. Perhaps it is there but I am not sure of what I am looking for. Hopefully someone here can help.

For interest, here is my program at present:

#include <iostream>
#include <fstream>

using namespace std;

struct StockItem
{
    int code;
    char desc[20];
    float price;
};

/*struct bill_line
{
    StockItem product;
    float weight;
    float cost;
};

struct bill
{
    bill_line items[20];
    int num_lines;
};*/

void disp_menu(void);
struct StockItem enter_data();
void see_stock(StockItem stock[125], int num_items);
void save_data(StockItem save);

main()
{
    StockItem stock[125];
    int ans;
    int num_items = 0;

    do
    {
        do
        {
            disp_menu();
            cin >> ans;
        } while ((ans<1) || (ans>5));

        switch (ans)
        {
            case 1: 
                stock[num_items] = enter_data();
                num_items++;
                break; 
            case 2: 
                see_stock(stock, num_items);
                break;
            case 3:
                save_data(*stock);
                break;
            default:
                break;
        } 
    }while (ans!=6);

    return 0;

    system("PAUSE");
    return 0;
}

void disp_menu()
{
    cout << "\n*** The Corner Shop ***\n\n";
    cout << "Select an option: \n\n";
    cout << "\t1. Enter new stock " << endl;
    cout << "\t2. See current stock " << endl;
    cout << "\t3. Exit \n" << endl;
    cout << "option> ";
}

StockItem enter_data()
{
    StockItem stock_item;

    cout << "\n\nWhat is the product code: ";
    cin >> stock_item.code;
    cout << "What is the product description: ";
    fflush(stdin);
    cin.getline(stock_item.desc, 20);
    cout << "What is the product price: ";
    cin >> stock_item.price;  

    return (stock_item);
}

void see_stock(StockItem stock[125], int num_items)
{
    int ctr;
    char ret;

    cout << "\n\nHere is the stock listing:\n\n";
    for (ctr = 0; ctr < num_items; ++ctr)
    {
        cout << "Item " << ctr+1 << endl;
        cout << "Product Code: " << stock[ctr].code <<  endl;
        cout << "Product Description: " << stock[ctr].desc << endl;
        cout << "Price: " << stock[ctr].price << endl;
        cout << "------------------------------------------------\n";
    }
    cout << "Press any key to return to the menu";
    if (cin >> ret) //how do you make this work on a keystroke, and not requiring input then enter??
    return;
}

//Problem section
void save_data(StockItem save)
{
    fstream fp;

    fp.open("items.txt", ios::in | ios::out);
    if (!fp)
    {
        cout << "\n*** Error opening file ***\n";
        exit(0);
    }
    fp << save;
    fp.close();
}

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Help with c++ program

ged.suse＠ntlworld.com