DataStructuresAndAlgorithms/Codes/Practical-F23 (Student information).cpp

/*
THIS CODE HAS BEEN TESTED AND IS FULLY OPERATIONAL.

Problem Statement: Department maintains a student information. The file contains roll number, name, division and address. Allow user to add, delete information of student. Display information of particular employee. If record of student does not exist an appropriate message is displayed. If it is, then the system displays the student details. Use sequential file to main the data.

Code from DataStructuresAndAlgorithms (SPPU - Second Year - Computer Engineering - Content) repository on KSKA Git: https://git.kska.io/sppu-se-comp-content/DataStructuresAndAlgorithms/
*/

// BEGINNING OF CODE
#include <cstring>
#include <fstream>
#include <iostream>
using namespace std;

typedef struct student {
    int rollNo;
    char name[50];
    char div;
    char address[100];
} student;

class studentDatabase {
    string fileName = "student_data.dat";

   public:
    studentDatabase() {
        fstream fileObj(fileName);
        if (fileObj.fail()) {
            fileObj.open(fileName, ios::out);
            cout << "New file created." << endl;
        } else {
            cout << "File already exists." << endl;
        }
        fileObj.close();
    }

    void addStudent();
    void searchStudent();
    void deleteStudent();
    void displayAll();
};

void studentDatabase::searchStudent() {
    int roll;
    student s;
    bool status = false;

    // take input of roll number to delete
    cout << "Roll number to search:\t";
    cin >> roll;

    // opening files to delete a record
    ifstream readFile;
    readFile.open(fileName, ios::in | ios::binary);

    // looking for record
    while (readFile.read((char*)&s, sizeof(student))) {
        if (s.rollNo == roll) {
            status = true;
            break;
        }
    }
    
    readFile.close();

    if (status) {
        cout << "--- RECORD FOUND ---" << endl;
        cout << "Roll number:\t" << s.rollNo << endl;
        cout << "Name:\t" << s.name << endl;
        cout << "Division:\t" << s.div << endl;
        cout << "Address:\t" << s.address << endl;
        cout << "--- END OF RECORD ---" << endl;
    } else {
        cout << "Record not found." << endl;
    }
}

void studentDatabase::deleteStudent() {
    int roll;
    student s;
    bool status = false;

    // take input of roll number to delete
    cout << "Roll number to delete:\t";
    cin >> roll;

    // opening files to delete a record
    ifstream readFile;
    readFile.open(fileName, ios::in | ios::binary);
    ofstream writeFile;
    writeFile.open("~" + fileName, ios::out | ios::binary);
    writeFile.clear();

    // looking for record
    while (readFile.read((char*)&s, sizeof(student))) {
        if (s.rollNo == roll) {
            status = true;
        } else {
            writeFile.write((char*)&s, sizeof(student)) << flush;
        }
    }
    readFile.close();
    writeFile.close();

    // moving temp file back to original file
    if (status) {
        readFile.open("~" + fileName, ios::in | ios::binary);
        writeFile.open(fileName, ios::out | ios::binary);
        writeFile.clear();

        writeFile << readFile.rdbuf();
        readFile.close();
        writeFile.close();

        // remove("~"+fileName);
        cout << "Record deleted." << endl;
    } else {
        cout << "Record not found." << endl;
    }
}

void studentDatabase::addStudent() {
    student s;
    cout << "Roll number:\t";
    cin >> s.rollNo;
    cout << "Name:\t";
    cin.ignore();
    cin.getline(s.name, 50);
    cout << "Division:\t";
    // cin.ignore();
    cin >> s.div;
    cout << "Address:\t";
    cin.ignore();
    cin.getline(s.address, 100);
    // cin.ignore();
    ofstream file(fileName, ios::out | ios::binary | ios::app);
    // file.seekp(ios::end);
    file.write((char*)&s, sizeof(student)) << flush;
    if (file.fail()) {
        cout << "Failed to add student record." << endl;
    } else {
        cout << "Student added successfully." << endl;
    }
    file.close();
}

void studentDatabase::displayAll() {
    ifstream file;
    student s;
    int count = 0;
    file.open(fileName, ios::in | ios::binary);
    while (file.read((char*)&s, sizeof(student))) {
        count++;
        cout << count << ") ";
        cout << s.rollNo << "|";
        cout << s.name << "|";
        cout << s.div << "|";
        cout << s.address << endl;
    }
    if (count == 0) {
        cout << "No records found." << endl;
    }
    file.close();
}
int main() {
    int ch;
    studentDatabase db;

    // loop
    do {
        cout << endl;
        cout << "--- MAIN MENU ---" << endl;
        cout << "1 -> Add record" << endl;
        cout << "2 -> Delete record" << endl;
        cout << "3 -> Search record" << endl;
        cout << "4 -> Display all records" << endl;
        cout << "0 -> Exit" << endl << endl;
        cout << "Choose an option (0-4):\t";
        cin >> ch;
        switch (ch) {
            case 0:
                cout << "\n\n// END OF CODE\n\n" << endl;
                break;
            case 1:
                db.addStudent();
                break;
            case 2:
                db.deleteStudent();
                break;
            case 3:
                db.searchStudent();
                break;
            case 4:
                cout << "All records are:\t" << endl;
                db.displayAll();
                break;

            default:
                cout << "Please choose a valid option (0-4):\t" << endl;
                break;
        }
    } while (ch != 0);

    return 0;
}
// END OF CODE