Blea_Database.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <limits> // Required for numeric_limits

using namespace std;

fstream file;
string filename = "data.txt";

struct Person {
    string id, firstName, lastName;
    int income;
};

Person* search(string id) {
    Person *p2 = new Person;
    char empId[6], firstName[16], lastName[16], incomeStr[11]; // Increased sizes by 1 for null terminator

    file.clear();
    file.seekg(0, ios::beg); // Rewind to the beginning for each search

    while (file.read(empId, 5)) {
        empId[5] = '\0';
        p2->id = empId;
        if (p2->id == id) {
            // Reading rest of data
            file.read(firstName, 15);
            firstName[15] = '\0'; // Null-terminate the string
            file.read(lastName, 15);
            lastName[15] = '\0'; // Null-terminate the string
            file.read(incomeStr, 10);
            incomeStr[10] = '\0'; // Null-terminate the string

            // Save to structure Person
            p2->firstName = firstName;
            p2->lastName = lastName;
            p2->income = stoi(incomeStr); // Use stoi for integer conversion
            return p2;
        }
        file.seekg(40, ios::cur);
    }

    delete p2; // Deallocate if not found
    return nullptr; // Return nullptr if not found
}

void get_employee() {
    string empId;
    cout << "Enter Employee id: ";
    cin >> empId;

    Person* employee = search(empId);
    if (employee == nullptr) {
        cout << "Employee not found." << endl;
    } else {
        cout << "Employee ID: " << employee->id << endl;
        cout << "First Name: " << employee->firstName << endl;
        cout << "Last Name: " << employee->lastName << endl;
        cout << "Income: " << employee->income << endl; // Fixed typo here
        delete employee;
    }
}

void list() {
    char id[6], firstName[16], lastName[16], incomeStr[11]; // Increased sizes by 1
    file.clear();
    file.seekg(0, ios::beg);
    while (file.read(id, 5)) {
        id[5] = '\0'; // Null-terminate the string
        file.read(firstName, 15);
        firstName[15] = '\0'; // Null-terminate the string
        file.read(lastName, 15);
        lastName[15] = '\0'; // Null-terminate the string
        file.read(incomeStr, 10);
        incomeStr[10] = '\0'; // Null-terminate the string

        // No need to convert to float here since income is an int in the struct
        cout << id << " " << firstName << " " << lastName << " " << incomeStr << endl;
    }
}

void write_data(Person p) {
    file.clear();
    file.write(p.id.c_str(), 5);
    file.write(p.firstName.c_str(), 15);
    file.write(p.lastName.c_str(), 15);
    file << p.income << endl; // Use endl for newline and implicit conversion to string
    file.flush();
}

void new_employee() {
    string empId;
    while (1) {
            cout << "\n*** New Employee ***\n";
            cout << "Enter employee id (-1 to end): ";
            cin >> empId;
            if (empId == "-1") break; // stop when user enters -1
            // search if the employee exist, call to search function
            // Remember search function return a pointer to struct ‘Person’ if the employee
            Person* employee = search(empId);
            // otherwise, it returns null pointer (i.e. zero pointer)
            // If the employee id exist, then exit from the function by calling return.
            if (employee != nullptr) {
                    cout << "Employee ID already exists." << endl;
                    return;
            }
            // If employee id does not exist, then continue ask the user about the employee
            // information: first name, last name, and income.
            // complete code
            // Save data to Person struct
            Person p;
            p.id = empId;
            cout << "Enter first name: ";
            cin >> p.firstName;
            cout << "Enter last name: ";
            cin >> p.lastName;
            cout << "Enter income: ";
            cin >> p.income;
            cout << "Saving data: ";
            write_data(p);
    }
}

int main() {
    file.open(filename, ios::in | ios::out); // open file for read and write
            if (!file) {
                    file.open(filename, ios::out); // create the file
                    file.close();
                    file.open(filename, ios::in | ios::out);
            }
            // Menu:
    int option = -1;
    while (1) {
            cout << "*** Menu ***" << endl;
            cout << "1) New employee\n";
            cout << "2) Search employee information\n";
            cout << "3) List employee\n";
            cout << "option: ";
            cin >> option;
            switch (option) {
                    case 1: new_employee(); break;
                    case 2: get_employee(); break;
                    case 3: list(); break;
                    default: // any other number will exit the menu loop
                            return 0;
                    }
            }
            // Close files
            file.close();
    return 0;
}