Library book managment using linked list

[Please rate my code.] This helps to maintain a book-list in a small library. The book information contains the title, author, publish year, and ISBN code. The information will be given to you in a text file books.txt. Each line of the file contains data about books. (For more information about this, look at the books.txt file in the zip file) It provides functions to: - add a book - delete a book based on the ISBN code or title - search for a book based on the ISBN code - list all books - list every books written by a specific author It also provides an easy way for users to select a command from a command menu to perform the above functions and to input data from the keyboard. The "books.txt" file is used to initialize the list.