database

#include <iostream>
#include <string>
#include <fstream> //form work with files

using namespace std;

const int MAX_USERS = 500;

struct User {
    string username;
    string password;
};

class PasswordDatabase {
private:
    User database[MAX_USERS];
    int count;

public:
    PasswordDatabase() : count(0) {}

    void addPassword(const string& username, const string& password) {
        if (count >= MAX_USERS) {
            cout << "Database is full!\n";
            return;
        }
        for (int i = 0; i < count; i++) {
            if (database[i].username == username) {
                cout << "Username already exists!\n";
                return;
            }
        }

        database[count].username = username;
        database[count].password = password;
        count++;
        cout << "Password added for user: " << username << endl;
    }

    void getPassword(const string& username) const {
        for (int i = 0; i < count; i++) {
            if (database[i].username == username) {
                cout << "Password for user " << username << ": " << database[i].password << endl;
                return;
            }
        }
        cout << "Username not found.\n";
    }

    void deletePassword(const string& username) {
        for (int i = 0; i < count; i++) {
            if (database[i].username == username) {
                for (int j = i; j < count - 1; j++) {
                    database[j] = database[j + 1];
                }
                count--;
                cout << "Password for user " << username << " deleted.\n";
                return;
            }
        }
        cout << "Username not found.\n";
    }

    void showAllUsers() const {
        if (count == 0) {
            cout << "Database is empty.\n";
        }
        else {
            cout << "User list:\n";
            for (int i = 0; i < count; i++) {
                cout << "User: " << database[i].username << ", Password: " << database[i].password << endl;
            }
        }
    }

    void saveToFile(const string& filename) const {
        ofstream file(filename);
        if (file.is_open()) {
            for (int i = 0; i < count; i++) {
                file << database[i].username << " " << database[i].password << endl;
            }
            file.close();
            cout << "Database saved to file: " << filename << endl;
        }
        else {
            cout << "Failed to open file for writing.\n";
        }
    }

    void loadFromFile(const string& filename) {
        ifstream file(filename);
        if (file.is_open()) {
            string username, password;
            while (file >> username >> password) {
                addPassword(username, password);
            }
            file.close();
            cout << "Database loaded from file: " << filename << endl;
        }
        else {
            cout << "Failed to open file for reading.\n";
        }
    }
};

void showMenu() {
    cout << "\n=== Password Database Menu ===\n";
    cout << "1. Add password\n";
    cout << "2. Get password\n";
    cout << "3. Delete password\n";
    cout << "4. Show all users\n";
    cout << "5. Save database to file\n";
    cout << "6. Load database from file\n";
    cout << "0. Exit\n";
    cout << "Choose an option: ";
}

int main() {
    PasswordDatabase db;
    int choice;
    string username, password, filename;

    cout << "Create by Yaroslav Yatsenko\n";

    do {
        showMenu();
        cin >> choice;

        switch (choice) {
        case 1:
            cout << "Enter username: ";
            cin >> username;
            cout << "Enter password: ";
            cin >> password;
            db.addPassword(username, password);
            break;
        case 2:
            cout << "Enter username: ";
            cin >> username;
            db.getPassword(username);
            break;
        case 3:
            cout << "Enter username: ";
            cin >> username;
            db.deletePassword(username);
            break;
        case 4:
            db.showAllUsers();
            break;
        case 5:
            cout << "Enter filename: ";
            cin >> filename;
            db.saveToFile(filename);
            break;
        case 6:
            cout << "Enter filename: ";
            cin >> filename;
            db.loadFromFile(filename);
            break;
        case 0:
            cout << "Exiting program. Goodbye!\n";
            break;
        default:
            cout << "Invalid choice. Please try again.\n";
        }
    } while (choice != 0);

    return 0;
}