YZU_CSE_HW8.cpp

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;

struct DATA{
    int record, quantity;
    char name[80];
    float price;
};
struct DATA data[100];

void initialize_dat(){
    ofstream file;
    file.open("fruits.dat", ios::out | ios::binary);
    for (int i=0; i<100; i++) {
        file.write(reinterpret_cast<char *>(&data[i].record), sizeof(data[i].record));
        file.write(reinterpret_cast<char *>(&data[i].name), sizeof(data[i].name));
        file.write(reinterpret_cast<char *>(&data[i].quantity), sizeof(data[i].quantity));
        file.write(reinterpret_cast<char *>(&data[i].price), sizeof(data[i].price));
    }
    file.close();
}

void load_dat(){
    ifstream fruit;
    fruit.open("fruits.dat", ios::in | ios::binary);
    while (!fruit.eof()) {
        int id, num;
        char name[80];
        float price;
        fruit.read(reinterpret_cast<char *>(&id), sizeof(id));
        fruit.read(reinterpret_cast<char *>(&name), sizeof(name));
        fruit.read(reinterpret_cast<char *>(&num), sizeof(num));
        fruit.read(reinterpret_cast<char *>(&price), sizeof(price));
        data[id].record = id;
        data[id].price = price;
        data[id].quantity = num;
        strcpy(data[id].name, name);
    }
    fruit.close();
}

void list_dat(){
    cout << setw(7) << "Record#" << setw(13) << "Fruit Name" << setw(10) << "Quantity" << setw(8) << "Price" << "\n";
    for (int i=0; i<100; i++) {
        if (data[i].record == -1) {
            continue;
        }
        cout << setw(7) << data[i].record << setw(13) << data[i].name << setw(10) << data[i].quantity << setw(8) << fixed << setprecision(2) << data[i].price << "\n";
    }
}

void update_record(){
    int record, quantity;
    float price;
    char name[80];
    cout << "Which record to update? ";
    cin >> record;
    if (data[record].record==-1) {
        cout << "Cannot update. The record is empty.\n";
    }
    else{
        cout << setw(7) << "Record#" << setw(13) << "Fruit Name" << setw(10) << "Quantity" << setw(8) << "Price" << "\n";
        cout << setw(7) << data[record].record << setw(13) << data[record].name << setw(10) << data[record].quantity << setw(8) << fixed << setprecision(2) << data[record].price << "\n";
        cout << "Name: ";
        cin >> name;
        cout << "Quantity: ";
        cin >> quantity;
        cout << "Price: ";
        cin >> price;
        data[record].quantity = quantity;
        data[record].price = price;
        strcpy(data[record].name, name);
        cout << "Record updated.\n";
    }
    
}

void insert(){
    int count = 0;
    for (int i=0; i<100; i++) {
        if (data[i].record!=-1) {
            count++;
        }
    }
    if (count==100) {
        cout << "Cannot insert. The file is full.\n";
    }
    else{
        int record, quantity;
        float price;
        char name[80];
        cout << "Record: ";
        cin >> record;
        cout << "Name: ";
        cin >> name;
        cout << "Quantity: ";
        cin >> quantity;
        cout << "Price: ";
        cin >> price;
        data[record].record = record;
        data[record].quantity = quantity;
        data[record].price = price;
        strcpy(data[record].name, name);
        cout << "Record inserted.\n";
    }
}

void Delete(){
    int num;
    cout << "Which record would you like to delete: ";
    cin >> num;
    data[num].record = -1;
    data[num].price = 0.00;
    data[num].quantity = 0;
    strcpy(data[num].name, "");
}

void save(){
    ofstream file;
    file.open("fruits.dat", ios::out | ios::binary);
    for (int i=0; i<100; i++) {
        file.write(reinterpret_cast<char *>(&data[i].record), sizeof(data[i].record));
        file.write(reinterpret_cast<char *>(&data[i].name), sizeof(data[i].name));
        file.write(reinterpret_cast<char *>(&data[i].quantity), sizeof(data[i].quantity));
        file.write(reinterpret_cast<char *>(&data[i].price), sizeof(data[i].price));
    }
    file.close();
}

int main(){
    for (int i=0; i<100; i++) {
        data[i].record = -1;
        data[i].price = 0.00;
        data[i].quantity = 0;
        strcpy(data[i].name, "");
        
    }
    ifstream fruit;
    fruit.open("fruits.dat", ios::in | ios::binary);
    if (!fruit) {
        fruit.close();
        initialize_dat();
    }
    load_dat();
    cout << "Data of fruits.dat is loaded!\n\n";
    int choice=-1;
    cout << "Enter a choice:\n1  List all fruits.\n2  Update record.\n3  Insert record.\n4  Delete record.\n5  End program.\n";
    while (choice!=5) {
        cout << "?";
        cin >> choice;
        switch (choice) {
            case 1:
                list_dat();
                break;
            case 2:
                update_record();
                break;
            case 3:
                insert();
                break;
            case 4:
                Delete();
                break;
            default:
                break;
        }
    }
    save();
    
}