System Implementation: Modular Files, Persistence & Exception Handling

Explanation

Project implementation translates architecture into executable, deployment-grade software. The integration of binary streams with OOP class structures allows persistent simulation of enterprise databases without requiring heavy external database engines.

Key points

• Applying core OOP features: Inheritance hierarchies, constructor chaining, operator overloading, and dynamic polymorphism.
• Persistent Storage: Managing binary file streams (ifstream, ofstream, fstream) to perform full CRUD operations (Create, Read, Update, Delete) on domain records.
• Robust Input Validation: Preventing buffer overflows, handling bad numeric input (cin.fail(), cin.clear(), cin.ignore()), and throwing custom exception classes.
• Clean Code Practices: Meaningful identifiers, const-correctness, zero memory leaks, and informative comments.

Example

Code examples

// Modular C++ File-Persistence Architecture for Project-II
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

class Book {
public:
    int bookId;
    char title[50];
    char author[50];
    bool isIssued;

    void input() {
        cout << "Enter Book ID: "; cin >> bookId;
        cin.ignore();
        cout << "Enter Title: "; cin.getline(title, 50);
        cout << "Enter Author: "; cin.getline(author, 50);
        isIssued = false;
    }

    void display() const {
        cout << "[" << bookId << "] " << title << " by " << author 
             << (isIssued ? " (ISSUED)" : " (AVAILABLE)") << endl;
    }
};

class LibraryManager {
private:
    const char* filename = "library.dat";
public:
    void addBook(const Book& b) {
        ofstream out(filename, ios::binary | ios::app);
        out.write(reinterpret_cast<const char*>(&b), sizeof(Book));
        out.close();
    }

    bool updateStatus(int targetId, bool status) {
        fstream file(filename, ios::binary | ios::in | ios::out);
        Book b;
        while (file.read(reinterpret_cast<char*>(&b), sizeof(Book))) {
            if (b.bookId == targetId) {
                b.isIssued = status;
                file.seekp(-static_cast<int>(sizeof(Book)), ios::cur);
                file.write(reinterpret_cast<const char*>(&b), sizeof(Book));
                file.close();
                return true;
            }
        }
        file.close();
        return false;
    }
};

Exam questions

• [10 Marks] Write a C++ program implementing an in-place record update and deletion algorithm on a binary file using seekg/seekp.
• [5 Marks] Explain why header guards (#ifndef, #define, #endif) are necessary in multi-file C++ projects.