Student Management System.cpp

/*
 * ============================================================
 *   Student Management System
 *   Console-based | File Handling | Menu-Driven
 *   Developed for Thiranex Internship - Task 1
 * ============================================================
 */

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
#include <iomanip>
#include <limits>
#include <algorithm>

using namespace std;

// ─────────────────────────────────────────
//  Student Structure
// ─────────────────────────────────────────
struct Student {
    int    id;
    string name;
    int    age;
    string department;
    double cgpa;
    string email;
};

// ─────────────────────────────────────────
//  Constants
// ─────────────────────────────────────────
const string DATA_FILE = "students.dat";
const string SEPARATOR = "|";

// ─────────────────────────────────────────
//  Utility: Clear screen (cross-platform)
// ─────────────────────────────────────────
void clearScreen() {
#ifdef _WIN32
    system("cls");
#else
    system("clear");
#endif
}

// ─────────────────────────────────────────
//  Utility: Print horizontal line
// ─────────────────────────────────────────
void printLine(char c = '-', int len = 65) {
    cout << string(len, c) << "\n";
}

// ─────────────────────────────────────────
//  Utility: Print banner
// ─────────────────────────────────────────
void printBanner() {
    clearScreen();
    printLine('=');
    cout << setw(48) << "  STUDENT MANAGEMENT SYSTEM\n";
    cout << setw(48) << "     Thiranex Internship — Task 1\n";
    printLine('=');
    cout << "\n";
}

// ─────────────────────────────────────────
//  Utility: Safe integer input
// ─────────────────────────────────────────
int getInt(const string& prompt) {
    int val;
    while (true) {
        cout << prompt;
        if (cin >> val) {
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
            return val;
        }
        cout << "  [!] Invalid input. Please enter a number.\n";
        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
    }
}

// ─────────────────────────────────────────
//  Utility: Safe double input
// ─────────────────────────────────────────
double getDouble(const string& prompt) {
    double val;
    while (true) {
        cout << prompt;
        if (cin >> val && val >= 0.0 && val <= 10.0) {
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
            return val;
        }
        cout << "  [!] Enter a valid CGPA between 0.0 and 10.0.\n";
        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
    }
}

// ─────────────────────────────────────────
//  Utility: Safe string input
// ─────────────────────────────────────────
string getString(const string& prompt) {
    string val;
    cout << prompt;
    getline(cin, val);
    return val;
}

// ─────────────────────────────────────────
//  File: Serialize one student to a line
// ─────────────────────────────────────────
string serialize(const Student& s) {
    ostringstream oss;
    oss << s.id << SEPARATOR
        << s.name << SEPARATOR
        << s.age << SEPARATOR
        << s.department << SEPARATOR
        << fixed << setprecision(2) << s.cgpa << SEPARATOR
        << s.email;
    return oss.str();
}

// ─────────────────────────────────────────
//  File: Deserialize a line to a student
// ─────────────────────────────────────────
bool deserialize(const string& line, Student& s) {
    istringstream iss(line);
    string token;
    try {
        if (!getline(iss, token, '|')) return false; s.id         = stoi(token);
        if (!getline(iss, token, '|')) return false; s.name       = token;
        if (!getline(iss, token, '|')) return false; s.age        = stoi(token);
        if (!getline(iss, token, '|')) return false; s.department = token;
        if (!getline(iss, token, '|')) return false; s.cgpa       = stod(token);
        if (!getline(iss, token, '|')) return false; s.email      = token;
        return true;
    } catch (...) {
        return false;
    }
}

// ─────────────────────────────────────────
//  File: Load all students from file
// ─────────────────────────────────────────
vector<Student> loadAll() {
    vector<Student> students;
    ifstream file(DATA_FILE);
    if (!file.is_open()) return students;
    string line;
    while (getline(file, line)) {
        if (line.empty()) continue;
        Student s;
        if (deserialize(line, s))
            students.push_back(s);
    }
    file.close();
    return students;
}

// ─────────────────────────────────────────
//  File: Save all students to file
// ─────────────────────────────────────────
void saveAll(const vector<Student>& students) {
    ofstream file(DATA_FILE, ios::trunc);
    for (const auto& s : students)
        file << serialize(s) << "\n";
    file.close();
}

// ─────────────────────────────────────────
//  Utility: Generate next unique ID
// ─────────────────────────────────────────
int nextId(const vector<Student>& students) {
    int maxId = 1000;
    for (const auto& s : students)
        if (s.id > maxId) maxId = s.id;
    return maxId + 1;
}

// ─────────────────────────────────────────
//  Utility: Print table header
// ─────────────────────────────────────────
void printTableHeader() {
    printLine('-');
    cout << left
         << setw(6)  << "ID"
         << setw(20) << "Name"
         << setw(5)  << "Age"
         << setw(15) << "Department"
         << setw(7)  << "CGPA"
         << setw(24) << "Email"
         << "\n";
    printLine('-');
}

// ─────────────────────────────────────────
//  Utility: Print one student row
// ─────────────────────────────────────────
void printRow(const Student& s) {
    cout << left
         << setw(6)  << s.id
         << setw(20) << s.name
         << setw(5)  << s.age
         << setw(15) << s.department
         << setw(7)  << fixed << setprecision(2) << s.cgpa
         << setw(24) << s.email
         << "\n";
}

// ─────────────────────────────────────────
//  FEATURE 1: Add Student
// ─────────────────────────────────────────
void addStudent() {
    printBanner();
    cout << "  [ ADD NEW STUDENT ]\n\n";

    vector<Student> students = loadAll();

    Student s;
    s.id         = nextId(students);
    s.name       = getString("  Full Name       : ");
    s.age        = getInt   ("  Age             : ");
    s.department = getString("  Department      : ");
    s.cgpa       = getDouble("  CGPA (0.0-10.0) : ");
    s.email      = getString("  Email           : ");

    students.push_back(s);
    saveAll(students);

    cout << "\n  [✓] Student added successfully! (ID: " << s.id << ")\n";
}

// ─────────────────────────────────────────
//  FEATURE 2: Display All Students
// ─────────────────────────────────────────
void displayAll() {
    printBanner();
    cout << "  [ ALL STUDENT RECORDS ]\n\n";

    vector<Student> students = loadAll();

    if (students.empty()) {
        cout << "  No records found.\n";
        return;
    }

    printTableHeader();
    for (const auto& s : students)
        printRow(s);
    printLine('-');
    cout << "  Total records: " << students.size() << "\n";
}

// ─────────────────────────────────────────
//  FEATURE 3: Search Student
// ─────────────────────────────────────────
void searchStudent() {
    printBanner();
    cout << "  [ SEARCH STUDENT ]\n\n";
    cout << "  Search by:  1. ID   2. Name\n";
    int choice = getInt("  Choice: ");

    vector<Student> students = loadAll();
    vector<Student> results;

    if (choice == 1) {
        int id = getInt("  Enter Student ID: ");
        for (const auto& s : students)
            if (s.id == id) results.push_back(s);
    } else {
        string keyword = getString("  Enter Name (partial ok): ");
        string kLower  = keyword;
        transform(kLower.begin(), kLower.end(), kLower.begin(), ::tolower);
        for (const auto& s : students) {
            string nLower = s.name;
            transform(nLower.begin(), nLower.end(), nLower.begin(), ::tolower);
            if (nLower.find(kLower) != string::npos)
                results.push_back(s);
        }
    }

    cout << "\n";
    if (results.empty()) {
        cout << "  No matching student found.\n";
        return;
    }
    printTableHeader();
    for (const auto& s : results) printRow(s);
    printLine('-');
    cout << "  Found: " << results.size() << " record(s).\n";
}

// ─────────────────────────────────────────
//  FEATURE 4: Update Student
// ─────────────────────────────────────────
void updateStudent() {
    printBanner();
    cout << "  [ UPDATE STUDENT RECORD ]\n\n";
    int id = getInt("  Enter Student ID to update: ");

    vector<Student> students = loadAll();
    bool found = false;

    for (auto& s : students) {
        if (s.id == id) {
            found = true;
            cout << "\n  Current Record:\n";
            printTableHeader();
            printRow(s);
            printLine('-');

            cout << "\n  Enter new details (press Enter to keep current):\n\n";

            auto updateField = [](const string& prompt, const string& current) -> string {
                cout << "  " << prompt << " [" << current << "]: ";
                string val;
                getline(cin, val);
                return val.empty() ? current : val;
            };

            s.name       = updateField("Full Name      ", s.name);
            string ageStr = updateField("Age            ", to_string(s.age));
            s.age        = stoi(ageStr);
            s.department = updateField("Department     ", s.department);

            string cgpaStr = updateField("CGPA           ", to_string(s.cgpa));
            double newCgpa = stod(cgpaStr);
            s.cgpa = (newCgpa >= 0.0 && newCgpa <= 10.0) ? newCgpa : s.cgpa;

            s.email = updateField("Email          ", s.email);
            break;
        }
    }

    if (!found) {
        cout << "\n  [!] Student with ID " << id << " not found.\n";
        return;
    }

    saveAll(students);
    cout << "\n  [✓] Student record updated successfully!\n";
}

// ─────────────────────────────────────────
//  FEATURE 5: Delete Student
// ─────────────────────────────────────────
void deleteStudent() {
    printBanner();
    cout << "  [ DELETE STUDENT RECORD ]\n\n";
    int id = getInt("  Enter Student ID to delete: ");

    vector<Student> students = loadAll();
    auto it = remove_if(students.begin(), students.end(),
                        [id](const Student& s) { return s.id == id; });

    if (it == students.end()) {
        cout << "\n  [!] Student with ID " << id << " not found.\n";
        return;
    }

    // Confirm deletion
    printTableHeader();
    printRow(*it);
    printLine('-');
    cout << "\n  Are you sure you want to delete this record? (y/n): ";
    char confirm;
    cin >> confirm;
    cin.ignore();

    if (tolower(confirm) != 'y') {
        cout << "  [!] Deletion cancelled.\n";
        return;
    }

    students.erase(it, students.end());
    saveAll(students);
    cout << "\n  [✓] Student record deleted successfully!\n";
}

// ─────────────────────────────────────────
//  FEATURE 6: Statistics
// ─────────────────────────────────────────
void showStatistics() {
    printBanner();
    cout << "  [ STATISTICS ]\n\n";

    vector<Student> students = loadAll();
    if (students.empty()) {
        cout << "  No records found.\n";
        return;
    }

    double totalCgpa = 0, maxCgpa = students[0].cgpa, minCgpa = students[0].cgpa;
    Student* topper = &students[0];

    for (auto& s : students) {
        totalCgpa += s.cgpa;
        if (s.cgpa > maxCgpa) { maxCgpa = s.cgpa; topper = &s; }
        if (s.cgpa < minCgpa)   minCgpa = s.cgpa;
    }

    cout << "  Total Students   : " << students.size() << "\n";
    cout << "  Average CGPA     : " << fixed << setprecision(2) << totalCgpa / students.size() << "\n";
    cout << "  Highest CGPA     : " << maxCgpa << " (" << topper->name << ")\n";
    cout << "  Lowest CGPA      : " << minCgpa << "\n";
}

// ─────────────────────────────────────────
//  Main Menu
// ─────────────────────────────────────────
void showMenu() {
    cout << "\n";
    printLine('-');
    cout << "   MENU\n";
    printLine('-');
    cout << "   1. Add Student\n";
    cout << "   2. Display All Students\n";
    cout << "   3. Search Student\n";
    cout << "   4. Update Student\n";
    cout << "   5. Delete Student\n";
    cout << "   6. Statistics\n";
    cout << "   0. Exit\n";
    printLine('-');
}

// ─────────────────────────────────────────
//  Entry Point
// ─────────────────────────────────────────
int main() {
    int choice;
    do {
        printBanner();
        showMenu();
        choice = getInt("   Enter your choice: ");

        switch (choice) {
            case 1: addStudent();     break;
            case 2: displayAll();     break;
            case 3: searchStudent();  break;
            case 4: updateStudent();  break;
            case 5: deleteStudent();  break;
            case 6: showStatistics(); break;
            case 0:
                cout << "\n  Goodbye! — Thiranex Internship\n\n";
                break;
            default:
                cout << "\n  [!] Invalid choice. Try again.\n";
        }

        if (choice != 0) {
            cout << "\n  Press Enter to return to menu...";
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }

    } while (choice != 0);

    return 0;
}