task2.cpp

#include <iostream>
#include <vector>
#include <string>
using namespace std;

class Book
{
public:
    string title;
    string author;
    int bookID;
    bool isIssued;

    Book(int id, string t, string a)
    {
        bookID = id;
        title = t;
        author = a;
        isIssued = false;
    }
};

class Library
{
private:
    vector<Book> books;

public:
    void addBook()
    {
        int id;
        string title, author;
        cout << "Enter Book ID: ";
        cin >> id;

        // Check duplicate ID
        for (int i = 0; i < books.size(); i++)
        {
            if (books[i].bookID == id)
            {
                cout << "Error: Book ID already exists!\n";
                return;
            }
        }

        cin.ignore();
        cout << "Enter Book Title: ";
        getline(cin, title);
        cout << "Enter Author Name: ";
        getline(cin, author);

        books.push_back(Book(id, title, author));
        cout << "Book added successfully!\n";
    }

    void updateBook()
    {
        int id;
        cout << "Enter Book ID to update: ";
        cin >> id;

        for (int i = 0; i < books.size(); i++)
        {
            if (books[i].bookID == id)
            {
                cin.ignore();
                cout << "Enter New Title: ";
                getline(cin, books[i].title);
                cout << "Enter New Author: ";
                getline(cin, books[i].author);
                cout << "Book updated successfully!\n";
                return;
            }
        }
        cout << "Error: Book ID not found!\n";
    }

    void searchBook()
    {
        int id;
        cout << "Enter Book ID to search: ";
        cin >> id;

        for (int i = 0; i < books.size(); i++)
        {
            if (books[i].bookID == id)
            {
                cout << "Book Found!\n";
                cout << "ID: " << books[i].bookID
                     << "\nTitle: " << books[i].title
                     << "\nAuthor: " << books[i].author
                     << "\nStatus: " << (books[i].isIssued ? "Issued" : "Available") << "\n";
                return;
            }
        }
        cout << "Error: Book ID not found!\n";
    }

    void issueBook()
    {
        int id;
        cout << "Enter Book ID to issue: ";
        cin >> id;

        for (int i = 0; i < books.size(); i++)
        {
            if (books[i].bookID == id)
            {
                if (books[i].isIssued)
                {
                    cout << "Error: Book already issued!\n";
                    return;
                }
                books[i].isIssued = true;
                cout << "Book issued successfully!\n";
                return;
            }
        }
        cout << "Error: Book ID not found!\n";
    }

    void returnBook()
    {
        int id;
        cout << "Enter Book ID to return: ";
        cin >> id;

        for (int i = 0; i < books.size(); i++)
        {
            if (books[i].bookID == id)
            {
                if (!books[i].isIssued)
                {
                    cout << "Error: Book was not issued!\n";
                    return;
                }
                books[i].isIssued = false;
                cout << "Book returned successfully!\n";
                return;
            }
        }
        cout << "Error: Book ID not found!\n";
    }

    void displayBooks()
    {
        if (books.empty())
        {
            cout << "Library is empty!\n";
            return;
        }
        cout << "\n--- Library Books ---\n";
        for (int i = 0; i < books.size(); i++)
        {
            cout << "ID: " << books[i].bookID
                 << " | Title: " << books[i].title
                 << " | Author: " << books[i].author
                 << " | Status: " << (books[i].isIssued ? "Issued" : "Available") << "\n";
        }
    }
};

int main()
{
    Library lib;
    int choice;

    do
    {
        cout << "\n===== Library Management System =====\n";
        cout << "1. Add Book\n2. Update Book\n3. Search Book\n4. Issue Book\n";
        cout << "5. Return Book\n6. Display All Books\n0. Exit\n";
        cout << "Enter choice: ";
        cin >> choice;

        switch (choice)
        {
        case 1:
            lib.addBook();
            break;
        case 2:
            lib.updateBook();
            break;
        case 3:
            lib.searchBook();
            break;
        case 4:
            lib.issueBook();
            break;
        case 5:
            lib.returnBook();
            break;
        case 6:
            lib.displayBooks();
            break;
        case 0:
            cout << "Exiting...\n";
            break;
        default:
            cout << "Invalid choice! Try again.\n";
        }
    } while (choice != 0);

    return 0;
}