DSA Python Project – Library Book Management System

Program 1

# Library Book Management System
class Book:
    def __init__(self, id, title, author):
        self.id = id
        self.title = title
        self.author = author
        self.prev = None
        self.next = None

class Library:
    def __init__(self):
        self.head = None

    def add_book(self, id, title, author):
        if self.book_exists(id):
            print(f"Book with ID {id} already exists.")
            return

        new_book = Book(id, title, author)
        if self.head is None:
            self.head = new_book
        else:
            temp = self.head
            while temp.next:
                temp = temp.next
            temp.next = new_book
            new_book.prev = temp
        print("Book added successfully.")

    def book_exists(self, id):
        temp = self.head
        while temp:
            if temp.id == id:
                return True
            temp = temp.next
        return False

    def display_books(self):
        if not self.head:
            print("Library is empty.")
            return
        print("\nBooks in Library:")
        temp = self.head
        while temp:
            print(f"ID: {temp.id}, Title: {temp.title}, Author: {temp.author}")
            temp = temp.next

    def search_by_id(self, id):
        temp = self.head
        while temp:
            if temp.id == id:
                print(f"Book found: ID = {temp.id}, Title = {temp.title}, Author = {temp.author}")
                return
            temp = temp.next
        print(f"Book not found with ID {id}")

    def search_by_title(self, title):
        temp = self.head
        while temp:
            if temp.title.lower() == title.lower():
                print(f"Book found: ID = {temp.id}, Author = {temp.author}")
                return
            temp = temp.next
        print(f"Book not found with title '{title}'")

    def search_by_author(self, author):
        temp = self.head
        found = False
        while temp:
            if temp.author.lower() == author.lower():
                print(f"Book found: ID = {temp.id}, Title = {temp.title}, Author = {temp.author}")
                found = True
            temp = temp.next
        if not found:
            print(f"No books found by author '{author}'")

    def delete_book(self, id):
        temp = self.head
        while temp and temp.id != id:
            temp = temp.next

        if not temp:
            print("Book not found.")
            return

        print(f"Book found: ID = {temp.id}, Title = {temp.title}, Author = {temp.author}")
        choice = input("Are you sure you want to delete this book? (yes/no): ").strip().lower()
        if choice == 'yes':
            if temp.prev:
                temp.prev.next = temp.next
            else:
                self.head = temp.next

            if temp.next:
                temp.next.prev = temp.prev

            print("Book deleted successfully.")

    def update_book(self, id):
        temp = self.head
        while temp:
            if temp.id == id:
                temp.title = input("Enter new title: ").strip()
                temp.author = input("Enter new author: ").strip()
                print("Book updated successfully.")
                return
            temp = temp.next
        print("Book not found.")


def main():
    library = Library()

    while True:
        print("\n------------- Library Menu -----------")
        print("1. Add Book")
        print("2. Display Books")
        print("3. Search Book by Title")
        print("4. Delete Book by ID")
        print("5. Update Book by ID")
        print("6. Search Book by ID")
        print("7. Search Book by Author")
        print("8. Exit")
        print("--------------------------------------")

        try:
            choice = int(input("Enter your choice: "))
        except ValueError:
            print("Invalid input. Please enter a number.")
            continue

        if choice == 1:
            try:
                id = int(input("Enter Book ID: "))
                title = input("Enter Title: ").strip()
                author = input("Enter Author: ").strip()
                library.add_book(id, title, author)
            except ValueError:
                print("Invalid ID. Must be a number.")
        elif choice == 2:
            library.display_books()
        elif choice == 3:
            title = input("Enter title to search: ").strip()
            library.search_by_title(title)
        elif choice == 4:
            try:
                id = int(input("Enter Book ID to delete: "))
                library.delete_book(id)
            except ValueError:
                print("Invalid ID.")
        elif choice == 5:
            try:
                id = int(input("Enter Book ID to update: "))
                library.update_book(id)
            except ValueError:
                print("Invalid ID.")
        elif choice == 6:
            try:
                id = int(input("Enter Book ID to search: "))
                library.search_by_id(id)
            except ValueError:
                print("Invalid ID.")
        elif choice == 7:
            author = input("Enter author name to search: ").strip()
            library.search_by_author(author)
        elif choice == 8:
            print("Exiting program.")
            break
        else:
            print("Invalid choice! Please choose a valid option.")

if __name__ == "__main__":
    main()