DSAL_AS - Sequential File Handling

#include <iostream>
#include <stdio.h>
#include <fstream>
#include <iomanip>
using namespace std;


class SFH {
private:
    struct studentData {
        int roll;
        char name[20];
    } s;
public:
    void create();
    void display();
    void search(int);
    void removeRecord(int);
};

void SFH::create() {
    fstream outfile;
    outfile.open("student.data", ios::binary | ios::out);
    int records;
    cout << "Enter the number of records: "; cin >> records;
    while (records--) {
        cout << "Enter Student Roll: "; cin >> s.roll;
        cout << "Enter Student Name: "; cin >> s.name;
        outfile.write((char *)&s, sizeof(s));
    }
    cout << endl;
    outfile.close();
}

void SFH::display() {
    fstream infile;
    infile.open("student.data", ios::binary | ios::in);
    cout << "\nDisplaying data...\n" << endl;
    cout << "Roll" << "\t" << "Name" << endl;
    cout << "-------------------------------" << endl;
    while (infile.read((char *)&s, sizeof(s))) {
        cout << right << setw(3) << s.roll << "\t" << s.name << endl;
    }
    cout << endl;
    infile.close();
}

void SFH::search(int key) {
    fstream infile;
    infile.open("student.data", ios::binary | ios::in);
    while (infile.read((char *)&s, sizeof(s))) {
        if (s.roll == key) {
            cout << "\nRecord Found!\n" << endl;
            cout << "Roll" << "\t" << "Name" << endl;
            cout << "-------------------------------" << endl;
            cout << right << setw(3) << s.roll << "\t" << s.name << endl;
            cout << endl;
            infile.close();
            return;
        }
    }
    cout << "\nRecord Not Found!\n" << endl;
    cout << endl;
    infile.close();
}

void SFH::removeRecord(int key) {
    // TODO - Exception if record does not exist
    fstream tempfile, infile;
    infile.open("student.data", ios::binary | ios::in);
    tempfile.open("temp.data", ios::binary | ios::out);

    bool exists = false;
    while (infile.read(((char *)&s), sizeof(s))) {
        if (s.roll == key) {
            exists = true;
            break;
        }
    }

    if (exists) {
        while (infile.read(((char *)&s), sizeof(s))) {
            if (s.roll == key) continue;
            else {
                tempfile.write((char *)&s, sizeof(s));
            }
        }
        infile.close();
        tempfile.close();
        remove("student.data");
        rename("temp.data", "student.data");
        cout << "\nRecord Deleted Successfully\n" << endl;
    } else {
        infile.close();
        tempfile.close();
        cout << "\nRecord does not exist!\n" << endl;
    }


};


int main() {
    SFH obj;
    int choice;
    while (true) {
        cout << "----- MENU -----" << endl;
        cout << "1. Create" << endl;
        cout << "2. Display" << endl;
        cout << "3. Search" << endl;
        cout << "4. Delete" << endl;
        cout << "5. Exit" << endl;
        cout << "----------------" << endl;
        cout << "Enter your choice: "; cin >> choice;

        if (choice == 1) {
            obj.create();
        } else if (choice == 2) {
            obj.display();
        } else if (choice == 3) {
            int key;
            cout << "Enter Roll No. to be searched: "; cin >> key;
            obj.search(key);
        } else if (choice == 4) {
            int key;
            cout << "Enter the Roll No. to be deleted: "; cin >> key;
            obj.removeRecord(key);
        } else if (choice == 5) {
            cout << "Terminating Program..." << endl;
            break;
        } else {
            cout << "Invalid Choice" << endl;
        }

    }
    return 0;
}