Question

Write a C++ program that uses a structure to store the following inventory information in a file:

⦁   Item description, Quantity on hand, Wholesale cost, Retail cost, and Date added to inventory.
⦁   Use a char array for item description and date.
⦁   The program should have a menu that allows the user to perform the following tasks:
i.   Add a new record at the end of the file.
ii.   Display any record in the file.
iii.   Change any record in the file.
iv.   Display all records in the file.
v.   Exit the program (otherwise repeat menu)
⦁   Each of the above tasks should open/use/close the file
⦁   Input validation: The program should not accept quantities, or wholesale or retail costs < 0.
⦁   Do not forget to add a record will need to modify the open function to include append mode (ios::binary | ios::app).

This is what I have done so far, but I keep getting infinite loops due to the cin buffer.

// begin program
#include <iostream>
#include <fstream>
#include <cstring>

//Structure definition
struct Inventory
{
    char item[20];
    int qty;
    double wcost;
    double rcost;
    char date[10];
};
void print_itemInfo(Inventory inv)
{
    std::cout << "Item          :" << inv.item << std::endl;
    std::cout << "Quantity      :" << inv.qty << std::endl;
    std::cout << "Wholesale Cost:" << inv.wcost << std::endl;
    std::cout << "Retail Cost   :" << inv.rcost << std::endl;
    std::cout << "Date          :" << inv.date << std::endl;
}

//Function prototypes
void displayMenu();
char getChoice(char);
void addRecord();
void displayRecord();
void editRecord();
void displayAll();

const char filename[] = "data.dat";

// Main function
int main()
{
// variable declaration
    const char MAX_CHOICE = '5';
    char choice;

    do {
        displayMenu();
        choice = getChoice(MAX_CHOICE);   
        
        switch (choice)
        {
            case '1':
                addRecord();
                break;
            case '2':
                displayRecord();
                break;
            case '3':
                editRecord();
                break;
            case '4':
                displayRecord();
            default:
                std::cout << "invalid choice\n";
        }
    } while (choice != '5');
    return 0;
}
/************************************************************************
 *              displayMenu                                             *
 *  This function displays the user's menu on the screen                *
 ************************************************************************/
void displayMenu()
{
    // Menu choice
    std::cout << "\nMENU\n\n";
    std::cout << "1. Add Record\n";
    std::cout << "2. Display Record\n";
    std::cout << "3. Edit Record\n";
    std::cout << "4. Display All Records\n";
    std::cout << "5. Exit the program\n\n";
    std::cout << "Enter your choice:  ";
}
/*************************************************************************
 *              getChoice                                                *
 * This function gets, validates, and returns the user's choice.         *
 * ***********************************************************************/
char getChoice(char max)
{
     char choice = std::cin.get();
     std::cin.ignore();           // Bypass the '\n\ in the input buffer

     while (choice < '1' || choice > max)
     {
         std::cout << "Choice must be between 1 and " << max << ".  "
                   << "Please re-enter choice:  ";
         choice = std::cin.get();
         std::cin.ignore();       // Bypass the '\n\ in the input buffer
     }
     return choice;
}
// addRecord function
void addRecord()
{
    Inventory inv;
    std::fstream outfile(filename, std::ios::out | std::ios::app | std::ios::binary);

    // Get data from keyboard
    std::cout << "Enter item description\n";
    std::cin.ignore();
    std::cin.getline(inv.item, 20);
    std::cout << "Enter quantity\n";
    std::cin >> inv.qty;
    std::cout << "Enter wholesale cost\n";
    std::cin >> inv.wcost;
    std::cout << "Enter Retail cost\n";
    std::cin >> inv.rcost;
    std::cout << "Enter date:  \n";
    std::cin.ignore();
    std::cin.getline(inv.date, 10);
    std::cin.get();
    outfile.write(reinterpret_cast<char *>(&inv), sizeof(inv));
    outfile.close();
    std::cin.clear();
}
void displayRecord()
{
    Inventory inv;
    int recNum;
    std::fstream rwfile(filename, std::ios::in | std::ios::out | std::ios::binary);

    // Move to the desired record and display
    std::cout << "\nEnter the record number you wish to see:  \n";
    std::cin >> recNum;
    rwfile.seekg(recNum * sizeof(inv, std::ios::beg));
    rwfile.read(reinterpret_cast<char *> (&inv), sizeof(inv));
    std::cout << "This is the information for record:  " << recNum << std::endl;
    print_itemInfo(inv);
    std::cin.clear();
}
// displayAll function
void displayAll()
{
    std::fstream infile(filename, std::ios::in | std::ios::binary);
    Inventory inv;
    infile.read(reinterpret_cast<char *>(&inv), sizeof(inv));
    while (!infile.fail() || !infile.eof())
    {
        print_itemInfo(inv);
        infile.read(reinterpret_cast<char *>(&inv), sizeof(inv));
    }
    infile.clear();
        
// Close the file
    infile.close();
}

// Edit function definition
void editRecord() {
    Inventory inv;
    int recNum;
    std::fstream rwfile(filename, std::ios::in | std::ios::out | std::ios::binary);

    // Move to the desired record and display
    std::cout << "\nEnter the number of record to edit\n";
    std::cin >> recNum;
    rwfile.seekg(recNum * sizeof(inv, std::ios::beg));
    rwfile.read(reinterpret_cast<char *> (&inv), sizeof(inv));
    std::cout << "This is the record you want to edit:  \n";
    std::cout << "\nDescription\t";
    std::cout << inv.item;
    std::cout << "\nQuantity\t";
    std::cout << inv.qty;
    std::cout << "\nWholesale Cost\t";
    std::cout << inv.wcost;
    std::cout << "\nRetail Cost\t";
    std::cout << inv.rcost;
    std::cout << "\nDate\t";
    std::cout << inv.date;
    //std::cout << "\nEnter new data\n";
    std::cout << "\nEnter item description\n";
    std::cin.ignore();
    std::cin.getline(inv.item, 20);
    std::cout << "Enter quantity\n";
    std::cin >> inv.qty;
    std::cout << "Enter wholesale cost\n";
    std::cin >> inv.wcost;
    std::cout << "Enter retail cost\n";
    std::cin >> inv.rcost;
    std::cout << "Enter date:  ";
    std::cin.getline(inv.date, 10);
    rwfile.seekg(recNum * sizeof(inv), std::ios::beg);
    std::cin.get();
    std::cin.clear();

    //Close the file
    rwfile.close();

}

Answer 1

code:

#include <iostream>
#include <fstream>
#include <cstring>

//Structure definition
struct Inventory
{
    char item[20];
    int qty;
    double wcost;
    double rcost;
    char date[10];
};
void print_itemInfo(Inventory inv)
{
    std::cout << "Item          :" << inv.item << std::endl;
    std::cout << "Quantity      :" << inv.qty << std::endl;
    std::cout << "Wholesale Cost:" << inv.wcost << std::endl;
    std::cout << "Retail Cost   :" << inv.rcost << std::endl;
    std::cout << "Date          :" << inv.date << std::endl;
}

//Function prototypes
void displayMenu();
char getChoice(char);
void addRecord();
void displayRecord();
void editRecord();
void displayAll();

const char filename[] = "data.dat";

// Main function
int main()
{
// variable declaration
    const char MAX_CHOICE = '5';
    char choice;

    do {
        displayMenu();
        choice = getChoice(MAX_CHOICE);
      
        switch (choice)
        {
            case '1':
                addRecord();
                break;
            case '2':
                displayRecord();
                break;
            case '3':
                editRecord();
                break;
            case '4':
                displayAll();
                break;
            default:
                std::cout << "invalid choice\n";
            break;
        }
    } while (choice != '5');
    return 0;
}
/************************************************************************
*              displayMenu                                             *
* This function displays the user's menu on the screen                *
************************************************************************/
void displayMenu()
{
    // Menu choice
    std::cout << "\nMENU\n\n";
    std::cout << "1. Add Record\n";
    std::cout << "2. Display Record\n";
    std::cout << "3. Edit Record\n";
    std::cout << "4. Display All Records\n";
    std::cout << "5. Exit the program\n\n";
    std::cout << "Enter your choice: ";
}
/*************************************************************************
*              getChoice                                                *
* This function gets, validates, and returns the user's choice.         *
* ***********************************************************************/
char getChoice(char max)
{
     char choice;
     std::cin>>choice;
     std::cin.ignore();           // Bypass the '\n\ in the input buffer

     while (choice < '1' || choice > max)
     {
         std::cout << "Choice must be between 1 and " << max << ". "
                   << "Please re-enter choice: ";
         std::cin>>choice;
         std::cin.ignore();       // Bypass the '\n\ in the input buffer
     }
     return choice;
}
// addRecord function
void addRecord()
{
    Inventory inv;
    std::fstream outfile(filename, std::ios::out | std::ios::app | std::ios::binary);

    // Get data from keyboard
    std::cout << "Enter item description:\t";
    std::cin.ignore();
    std::cin.getline(inv.item, 20);
    std::cout << "Enter quantity:\t";
    std::cin >> inv.qty;
    std::cout << "Enter wholesale cost:\t";
    std::cin >> inv.wcost;
    std::cout << "Enter Retail cost:\t";
    std::cin >> inv.rcost;
    std::cout << "Enter date:\t";
    std::cin.ignore();
    std::cin.getline(inv.date, 10);
    std::cin.get();
    outfile.write(reinterpret_cast<char *>(&inv), sizeof(inv));
    outfile.close();
    std::cin.clear();
}
void displayRecord()
{
    Inventory inv;
    int recNum;
    std::fstream rwfile(filename, std::ios::in | std::ios::out | std::ios::binary);

    // Move to the desired record and display
    std::cout << "\nEnter the record number you wish to see: \n";
    std::cin >> recNum;
    rwfile.seekg(recNum * sizeof(inv, std::ios::beg));
    rwfile.read(reinterpret_cast<char *> (&inv), sizeof(inv));
    std::cout << "This is the information for record: " << recNum << std::endl;
    print_itemInfo(inv);
    std::cin.clear();
}
// displayAll function
void displayAll()
{
    std::fstream infile(filename, std::ios::in | std::ios::binary);
    Inventory inv;
    infile.read(reinterpret_cast<char *>(&inv), sizeof(inv));
    while (!infile.fail() || !infile.eof())
    {
        print_itemInfo(inv);
        infile.read(reinterpret_cast<char *>(&inv), sizeof(inv));
    }
    infile.clear();
      
// Close the file
    infile.close();
}

// Edit function definition
void editRecord() {
    Inventory inv;
    int recNum;
    std::fstream rwfile(filename, std::ios::in | std::ios::out | std::ios::binary);

    // Move to the desired record and display
    std::cout << "\nEnter the number of record to edit\n";
    std::cin >> recNum;
    rwfile.seekg(recNum * sizeof(inv, std::ios::beg));
    rwfile.read(reinterpret_cast<char *> (&inv), sizeof(inv));
    std::cout << "This is the record you want to edit: \n";
    std::cout << "\nDescription\t";
    std::cout << inv.item;
    std::cout << "\nQuantity\t";
    std::cout << inv.qty;
    std::cout << "\nWholesale Cost\t";
    std::cout << inv.wcost;
    std::cout << "\nRetail Cost\t";
    std::cout << inv.rcost;
    std::cout << "\nDate\t";
    std::cout << inv.date;
    //std::cout << "\nEnter new data\n";
    std::cout << "\nEnter item description\n";
    std::cin.ignore();
    std::cin.getline(inv.item, 20);
    std::cout << "Enter quantity\n";
    std::cin >> inv.qty;
    std::cout << "Enter wholesale cost\n";
    std::cin >> inv.wcost;
    std::cout << "Enter retail cost\n";
    std::cin >> inv.rcost;
    std::cout << "Enter date: ";
    std::cin.getline(inv.date, 10);
    rwfile.seekg(recNum * sizeof(inv), std::ios::beg);
    std::cin.get();
    std::cin.clear();

    //Close the file
    rwfile.close();

}

Note: I have modified the code and not getting infinite loops. Record numbers are storing with same number change it you will get the correct functionality of code.

Output: